diff --git a/.env.dist b/.env.dist
index d6271d57..726635ba 100644
--- a/.env.dist
+++ b/.env.dist
@@ -3,6 +3,7 @@ APP_ENV=
 SHORTENED_URL_SCHEMA=
 SHORTENED_URL_HOSTNAME=
 SHORTCODE_CHARS=
+DEFAULT_LOCALE=
 
 # Database
 DB_USER=
diff --git a/composer.json b/composer.json
index 0211ed05..b9be6c6d 100644
--- a/composer.json
+++ b/composer.json
@@ -21,10 +21,11 @@
         "zendframework/zend-servicemanager": "^3.0",
         "zendframework/zend-paginator": "^2.6",
         "zendframework/zend-config": "^2.6",
+        "zendframework/zend-i18n": "^2.7",
         "mtymek/expressive-config-manager": "^0.4",
+        "acelaya/zsm-annotated-services": "^0.2.0",
         "doctrine/orm": "^2.5",
         "guzzlehttp/guzzle": "^6.2",
-        "acelaya/zsm-annotated-services": "^0.2.0",
         "symfony/console": "^3.0"
     },
     "require-dev": {
diff --git a/config/autoload/translator.global.php b/config/autoload/translator.global.php
new file mode 100644
index 00000000..e3730927
--- /dev/null
+++ b/config/autoload/translator.global.php
@@ -0,0 +1,8 @@
+<?php
+return [
+
+    'translator' => [
+        'locale' => getenv('DEFAULT_LOCALE') ?: 'en',
+    ],
+
+];
diff --git a/data/docs/rest.md b/data/docs/rest.md
index 09147518..35f18e2a 100644
--- a/data/docs/rest.md
+++ b/data/docs/rest.md
@@ -15,6 +15,12 @@ Statuses:
 
 [TODO]
 
+## Language
+
+In order to set the application language, you have to pass it by using the Accept-Language header.
+
+If not provided or provided language is not supported, english (en_US) will be used.
+
 ## Endpoints
 
 #### Authenticate
diff --git a/module/CLI/config/translator.config.php b/module/CLI/config/translator.config.php
new file mode 100644
index 00000000..ae120db3
--- /dev/null
+++ b/module/CLI/config/translator.config.php
@@ -0,0 +1,14 @@
+<?php
+return [
+
+    'translator' => [
+        'translation_file_patterns' => [
+            [
+                'type' => 'gettext',
+                'base_dir' => __DIR__ . '/../lang',
+                'pattern' => '%s.mo',
+            ],
+        ],
+    ],
+
+];
diff --git a/module/CLI/lang/es.mo b/module/CLI/lang/es.mo
new file mode 100644
index 00000000..5d5830b3
Binary files /dev/null and b/module/CLI/lang/es.mo differ
diff --git a/module/CLI/lang/es.po b/module/CLI/lang/es.po
new file mode 100644
index 00000000..b8fd2f7a
--- /dev/null
+++ b/module/CLI/lang/es.po
@@ -0,0 +1,135 @@
+msgid ""
+msgstr ""
+"Project-Id-Version: Shlink 1.0\n"
+"POT-Creation-Date: 2016-07-21 15:54+0200\n"
+"PO-Revision-Date: 2016-07-21 15:56+0200\n"
+"Last-Translator: \n"
+"Language-Team: \n"
+"Language: es_ES\n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+"X-Generator: Poedit 1.8.7.1\n"
+"X-Poedit-Basepath: ..\n"
+"Plural-Forms: nplurals=2; plural=(n != 1);\n"
+"X-Poedit-SourceCharset: UTF-8\n"
+"X-Poedit-KeywordsList: translate;translatePlural\n"
+"X-Poedit-SearchPath-0: src\n"
+"X-Poedit-SearchPath-1: config\n"
+
+msgid "Generates a shortcode for provided URL and returns the short URL"
+msgstr ""
+"Genera un código corto para la URL proporcionada y devuelve la URL acortada"
+
+msgid "The long URL to parse"
+msgstr "La URL larga a procesar"
+
+msgid "A long URL was not provided. Which URL do you want to shorten?:"
+msgstr "No se ha proporcionado una URL larga. ¿Qué URL deseas acortar?"
+
+msgid "A URL was not provided!"
+msgstr "¡No se ha proporcionado una URL!"
+
+msgid "Processed URL:"
+msgstr "URL procesada:"
+
+msgid "Generated URL:"
+msgstr "URL generada:"
+
+#, php-format
+msgid "Provided URL \"%s\" is invalid. Try with a different one."
+msgstr "La URL proporcionada \"%s\" e inválida. Prueba con una diferente."
+
+msgid "Returns the detailed visits information for provided short code"
+msgstr ""
+"Devuelve la información detallada de visitas para el código corto "
+"proporcionado"
+
+msgid "The short code which visits we want to get"
+msgstr "El código corto del cual queremos obtener las visitas"
+
+msgid "Allows to filter visits, returning only those older than start date"
+msgstr ""
+"Permite filtrar las visitas, devolviendo sólo aquellas más antiguas que "
+"startDate"
+
+msgid "Allows to filter visits, returning only those newer than end date"
+msgstr ""
+"Permite filtrar las visitas, devolviendo sólo aquellas más nuevas que endDate"
+
+msgid "A short code was not provided. Which short code do you want to use?:"
+msgstr "No se prporcionó un código corto. ¿Qué código corto deseas usar?"
+
+msgid "Referer"
+msgstr "Origen"
+
+msgid "Date"
+msgstr "Fecha"
+
+msgid "Remote Address"
+msgstr "Dirección remota"
+
+msgid "User agent"
+msgstr "Agente de usuario"
+
+msgid "List all short URLs"
+msgstr "Listar todas las URLs cortas"
+
+#, php-format
+msgid "The first page to list (%s items per page)"
+msgstr "La primera página a listar (%s elementos por página)"
+
+msgid "Short code"
+msgstr "Código corto"
+
+msgid "Original URL"
+msgstr "URL original"
+
+msgid "Date created"
+msgstr "Fecha de creación"
+
+msgid "Visits count"
+msgstr "Número de visitas"
+
+msgid "You have reached last page"
+msgstr "Has alcanzado la última página"
+
+msgid "Continue with page"
+msgstr "Continuar con la página"
+
+msgid "Processes visits where location is not set yet"
+msgstr "Procesa las visitas donde la localización no ha sido establecida aún"
+
+msgid "Processing IP"
+msgstr "Procesando IP"
+
+msgid "Ignored localhost address"
+msgstr "Ignorada IP de localhost"
+
+#, php-format
+msgid "Address located at \"%s\""
+msgstr "Dirección localizada en \"%s\""
+
+msgid "Finished processing all IPs"
+msgstr "Finalizado el procesado de todas las IPs"
+
+msgid "Returns the long URL behind a short code"
+msgstr "Devuelve la URL larga detrás de un código corto"
+
+msgid "The short code to parse"
+msgstr "El código corto a convertir"
+
+msgid "A short code was not provided. Which short code do you want to parse?:"
+msgstr ""
+"No se proporcionó un código corto. ¿Qué código corto quieres convertir?"
+
+#, php-format
+msgid "No URL found for short code \"%s\""
+msgstr "No se ha encontrado ninguna URL para el código corto \"%s\""
+
+msgid "Long URL:"
+msgstr "URL larga:"
+
+#, php-format
+msgid "Provided short code \"%s\" has an invalid format."
+msgstr "El código corto proporcionado \"%s\" tiene un formato inválido."
diff --git a/module/CLI/src/Command/GenerateShortcodeCommand.php b/module/CLI/src/Command/GenerateShortcodeCommand.php
index 91cbd228..0a0af9eb 100644
--- a/module/CLI/src/Command/GenerateShortcodeCommand.php
+++ b/module/CLI/src/Command/GenerateShortcodeCommand.php
@@ -12,6 +12,7 @@ use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Output\OutputInterface;
 use Symfony\Component\Console\Question\Question;
 use Zend\Diactoros\Uri;
+use Zend\I18n\Translator\TranslatorInterface;
 
 class GenerateShortcodeCommand extends Command
 {
@@ -23,26 +24,37 @@ class GenerateShortcodeCommand extends Command
      * @var array
      */
     private $domainConfig;
+    /**
+     * @var TranslatorInterface
+     */
+    private $translator;
 
     /**
      * GenerateShortcodeCommand constructor.
      * @param UrlShortenerInterface|UrlShortener $urlShortener
+     * @param TranslatorInterface $translator
      * @param array $domainConfig
      *
-     * @Inject({UrlShortener::class, "config.url_shortener.domain"})
+     * @Inject({UrlShortener::class, "translator", "config.url_shortener.domain"})
      */
-    public function __construct(UrlShortenerInterface $urlShortener, array $domainConfig)
-    {
-        parent::__construct(null);
+    public function __construct(
+        UrlShortenerInterface $urlShortener,
+        TranslatorInterface $translator,
+        array $domainConfig
+    ) {
         $this->urlShortener = $urlShortener;
+        $this->translator = $translator;
         $this->domainConfig = $domainConfig;
+        parent::__construct(null);
     }
 
     public function configure()
     {
         $this->setName('shortcode:generate')
-             ->setDescription('Generates a shortcode for provided URL and returns the short URL')
-             ->addArgument('longUrl', InputArgument::REQUIRED, 'The long URL to parse');
+             ->setDescription(
+                 $this->translator->translate('Generates a shortcode for provided URL and returns the short URL')
+             )
+             ->addArgument('longUrl', InputArgument::REQUIRED, $this->translator->translate('The long URL to parse'));
     }
 
     public function interact(InputInterface $input, OutputInterface $output)
@@ -54,9 +66,10 @@ class GenerateShortcodeCommand extends Command
 
         /** @var QuestionHelper $helper */
         $helper = $this->getHelper('question');
-        $question = new Question(
-            '<question>A long URL was not provided. Which URL do you want to shorten?:</question> '
-        );
+        $question = new Question(sprintf(
+            '<question>%s</question> ',
+            $this->translator->translate('A long URL was not provided. Which URL do you want to shorten?:')
+        ));
 
         $longUrl = $helper->ask($input, $output, $question);
         if (! empty($longUrl)) {
@@ -70,7 +83,7 @@ class GenerateShortcodeCommand extends Command
 
         try {
             if (! isset($longUrl)) {
-                $output->writeln('<error>A URL was not provided!</error>');
+                $output->writeln(sprintf('<error>%s</error>', $this->translator->translate('A URL was not provided!')));
                 return;
             }
 
@@ -80,13 +93,16 @@ class GenerateShortcodeCommand extends Command
                 ->withHost($this->domainConfig['hostname']);
 
             $output->writeln([
-                sprintf('Processed URL <info>%s</info>', $longUrl),
-                sprintf('Generated URL <info>%s</info>', $shortUrl),
+                sprintf('%s <info>%s</info>', $this->translator->translate('Processed URL:'), $longUrl),
+                sprintf('%s <info>%s</info>', $this->translator->translate('Generated URL:'), $shortUrl),
             ]);
         } catch (InvalidUrlException $e) {
-            $output->writeln(
-                sprintf('<error>Provided URL "%s" is invalid. Try with a different one.</error>', $longUrl)
-            );
+            $output->writeln(sprintf(
+                '<error>' . $this->translator->translate(
+                    'Provided URL "%s" is invalid. Try with a different one.'
+                ) . '</error>',
+                $longUrl
+            ));
         }
     }
 }
diff --git a/module/CLI/src/Command/GetVisitsCommand.php b/module/CLI/src/Command/GetVisitsCommand.php
index e7221e5e..c25ba27a 100644
--- a/module/CLI/src/Command/GetVisitsCommand.php
+++ b/module/CLI/src/Command/GetVisitsCommand.php
@@ -13,6 +13,7 @@ use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Input\InputOption;
 use Symfony\Component\Console\Output\OutputInterface;
 use Symfony\Component\Console\Question\Question;
+use Zend\I18n\Translator\TranslatorInterface;
 
 class GetVisitsCommand extends Command
 {
@@ -20,35 +21,47 @@ class GetVisitsCommand extends Command
      * @var VisitsTrackerInterface
      */
     private $visitsTracker;
+    /**
+     * @var TranslatorInterface
+     */
+    private $translator;
 
     /**
      * GetVisitsCommand constructor.
      * @param VisitsTrackerInterface|VisitsTracker $visitsTracker
+     * @param TranslatorInterface $translator
      *
-     * @Inject({VisitsTracker::class})
+     * @Inject({VisitsTracker::class, "translator"})
      */
-    public function __construct(VisitsTrackerInterface $visitsTracker)
+    public function __construct(VisitsTrackerInterface $visitsTracker, TranslatorInterface $translator)
     {
-        parent::__construct(null);
         $this->visitsTracker = $visitsTracker;
+        $this->translator = $translator;
+        parent::__construct(null);
     }
 
     public function configure()
     {
         $this->setName('shortcode:visits')
-            ->setDescription('Returns the detailed visits information for provided short code')
-            ->addArgument('shortCode', InputArgument::REQUIRED, 'The short code which visits we want to get')
+            ->setDescription(
+                $this->translator->translate('Returns the detailed visits information for provided short code')
+            )
+            ->addArgument(
+                'shortCode',
+                InputArgument::REQUIRED,
+                $this->translator->translate('The short code which visits we want to get')
+            )
             ->addOption(
                 'startDate',
                 's',
                 InputOption::VALUE_OPTIONAL,
-                'Allows to filter visits, returning only those older than start date'
+                $this->translator->translate('Allows to filter visits, returning only those older than start date')
             )
             ->addOption(
                 'endDate',
                 'e',
                 InputOption::VALUE_OPTIONAL,
-                'Allows to filter visits, returning only those newer than end date'
+                $this->translator->translate('Allows to filter visits, returning only those newer than end date')
             );
     }
 
@@ -61,9 +74,10 @@ class GetVisitsCommand extends Command
 
         /** @var QuestionHelper $helper */
         $helper = $this->getHelper('question');
-        $question = new Question(
-            '<question>A short code was not provided. Which short code do you want to use?:</question> '
-        );
+        $question = new Question(sprintf(
+            '<question>%s</question> ',
+            $this->translator->translate('A short code was not provided. Which short code do you want to use?:')
+        ));
 
         $shortCode = $helper->ask($input, $output, $question);
         if (! empty($shortCode)) {
@@ -80,10 +94,10 @@ class GetVisitsCommand extends Command
         $visits = $this->visitsTracker->info($shortCode, new DateRange($startDate, $endDate));
         $table = new Table($output);
         $table->setHeaders([
-            'Referer',
-            'Date',
-            'Remote Address',
-            'User agent',
+            $this->translator->translate('Referer'),
+            $this->translator->translate('Date'),
+            $this->translator->translate('Remote Address'),
+            $this->translator->translate('User agent'),
         ]);
 
         foreach ($visits as $row) {
diff --git a/module/CLI/src/Command/ListShortcodesCommand.php b/module/CLI/src/Command/ListShortcodesCommand.php
index 1db1f3fb..e59aa903 100644
--- a/module/CLI/src/Command/ListShortcodesCommand.php
+++ b/module/CLI/src/Command/ListShortcodesCommand.php
@@ -13,6 +13,7 @@ use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Input\InputOption;
 use Symfony\Component\Console\Output\OutputInterface;
 use Symfony\Component\Console\Question\ConfirmationQuestion;
+use Zend\I18n\Translator\TranslatorInterface;
 
 class ListShortcodesCommand extends Command
 {
@@ -22,28 +23,37 @@ class ListShortcodesCommand extends Command
      * @var ShortUrlServiceInterface
      */
     private $shortUrlService;
+    /**
+     * @var TranslatorInterface
+     */
+    private $translator;
 
     /**
      * ListShortcodesCommand constructor.
      * @param ShortUrlServiceInterface|ShortUrlService $shortUrlService
+     * @param TranslatorInterface $translator
      *
-     * @Inject({ShortUrlService::class})
+     * @Inject({ShortUrlService::class, "translator"})
      */
-    public function __construct(ShortUrlServiceInterface $shortUrlService)
+    public function __construct(ShortUrlServiceInterface $shortUrlService, TranslatorInterface $translator)
     {
-        parent::__construct(null);
         $this->shortUrlService = $shortUrlService;
+        $this->translator = $translator;
+        parent::__construct(null);
     }
 
     public function configure()
     {
         $this->setName('shortcode:list')
-             ->setDescription('List all short URLs')
+             ->setDescription($this->translator->translate('List all short URLs'))
              ->addOption(
                  'page',
                  'p',
                  InputOption::VALUE_OPTIONAL,
-                 sprintf('The first page to list (%s items per page)', PaginableRepositoryAdapter::ITEMS_PER_PAGE),
+                 sprintf(
+                     $this->translator->translate('The first page to list (%s items per page)'),
+                     PaginableRepositoryAdapter::ITEMS_PER_PAGE
+                 ),
                  1
              );
     }
@@ -59,10 +69,10 @@ class ListShortcodesCommand extends Command
             $page++;
             $table = new Table($output);
             $table->setHeaders([
-                'Short code',
-                'Original URL',
-                'Date created',
-                'Visits count',
+                $this->translator->translate('Short code'),
+                $this->translator->translate('Original URL'),
+                $this->translator->translate('Date created'),
+                $this->translator->translate('Visits count'),
             ]);
 
             foreach ($result as $row) {
@@ -72,10 +82,14 @@ class ListShortcodesCommand extends Command
 
             if ($this->isLastPage($result)) {
                 $continue = false;
-                $output->writeln('<info>You have reached last page</info>');
+                $output->writeln(
+                    sprintf('<info>%s</info>', $this->translator->translate('You have reached last page'))
+                );
             } else {
                 $continue = $helper->ask($input, $output, new ConfirmationQuestion(
-                    sprintf('<question>Continue with page <bg=cyan;options=bold>%s</>? (y/N)</question> ', $page),
+                    sprintf('<question>' . $this->translator->translate(
+                        'Continue with page'
+                    ) . ' <bg=cyan;options=bold>%s</>? (y/N)</question> ', $page),
                     false
                 ));
             }
diff --git a/module/CLI/src/Command/ProcessVisitsCommand.php b/module/CLI/src/Command/ProcessVisitsCommand.php
index 19692e85..e9f95a7b 100644
--- a/module/CLI/src/Command/ProcessVisitsCommand.php
+++ b/module/CLI/src/Command/ProcessVisitsCommand.php
@@ -11,6 +11,7 @@ use Shlinkio\Shlink\Core\Service\VisitServiceInterface;
 use Symfony\Component\Console\Command\Command;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Output\OutputInterface;
+use Zend\I18n\Translator\TranslatorInterface;
 
 class ProcessVisitsCommand extends Command
 {
@@ -24,25 +25,36 @@ class ProcessVisitsCommand extends Command
      * @var IpLocationResolverInterface
      */
     private $ipLocationResolver;
+    /**
+     * @var TranslatorInterface
+     */
+    private $translator;
 
     /**
      * ProcessVisitsCommand constructor.
      * @param VisitServiceInterface|VisitService $visitService
      * @param IpLocationResolverInterface|IpLocationResolver $ipLocationResolver
+     * @param TranslatorInterface $translator
      *
-     * @Inject({VisitService::class, IpLocationResolver::class})
+     * @Inject({VisitService::class, IpLocationResolver::class, "translator"})
      */
-    public function __construct(VisitServiceInterface $visitService, IpLocationResolverInterface $ipLocationResolver)
-    {
-        parent::__construct(null);
+    public function __construct(
+        VisitServiceInterface $visitService,
+        IpLocationResolverInterface $ipLocationResolver,
+        TranslatorInterface $translator
+    ) {
         $this->visitService = $visitService;
         $this->ipLocationResolver = $ipLocationResolver;
+        $this->translator = $translator;
+        parent::__construct(null);
     }
 
     public function configure()
     {
         $this->setName('visit:process')
-             ->setDescription('Processes visits where location is not set already');
+             ->setDescription(
+                 $this->translator->translate('Processes visits where location is not set yet')
+             );
     }
 
     public function execute(InputInterface $input, OutputInterface $output)
@@ -51,9 +63,11 @@ class ProcessVisitsCommand extends Command
 
         foreach ($visits as $visit) {
             $ipAddr = $visit->getRemoteAddr();
-            $output->write(sprintf('Processing IP <info>%s</info>', $ipAddr));
+            $output->write(sprintf('%s <info>%s</info>', $this->translator->translate('Processing IP'), $ipAddr));
             if ($ipAddr === self::LOCALHOST) {
-                $output->writeln(' (<comment>Ignored localhost address</comment>)');
+                $output->writeln(
+                    sprintf(' (<comment>%s</comment>)', $this->translator->translate('Ignored localhost address'))
+                );
                 continue;
             }
 
@@ -63,12 +77,15 @@ class ProcessVisitsCommand extends Command
                 $location->exchangeArray($result);
                 $visit->setVisitLocation($location);
                 $this->visitService->saveVisit($visit);
-                $output->writeln(sprintf(' (Address located at "%s")', $location->getCityName()));
+                $output->writeln(sprintf(
+                    ' (' . $this->translator->translate('Address located at "%s"') . ')',
+                    $location->getCityName()
+                ));
             } catch (WrongIpException $e) {
                 continue;
             }
         }
 
-        $output->writeln('Finished processing all IPs');
+        $output->writeln($this->translator->translate('Finished processing all IPs'));
     }
 }
diff --git a/module/CLI/src/Command/ResolveUrlCommand.php b/module/CLI/src/Command/ResolveUrlCommand.php
index 01dad903..62d81f41 100644
--- a/module/CLI/src/Command/ResolveUrlCommand.php
+++ b/module/CLI/src/Command/ResolveUrlCommand.php
@@ -11,6 +11,7 @@ use Symfony\Component\Console\Input\InputArgument;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Output\OutputInterface;
 use Symfony\Component\Console\Question\Question;
+use Zend\I18n\Translator\TranslatorInterface;
 
 class ResolveUrlCommand extends Command
 {
@@ -18,24 +19,34 @@ class ResolveUrlCommand extends Command
      * @var UrlShortenerInterface
      */
     private $urlShortener;
+    /**
+     * @var TranslatorInterface
+     */
+    private $translator;
 
     /**
      * ResolveUrlCommand constructor.
      * @param UrlShortenerInterface|UrlShortener $urlShortener
+     * @param TranslatorInterface $translator
      *
-     * @Inject({UrlShortener::class})
+     * @Inject({UrlShortener::class, "translator"})
      */
-    public function __construct(UrlShortenerInterface $urlShortener)
+    public function __construct(UrlShortenerInterface $urlShortener, TranslatorInterface $translator)
     {
-        parent::__construct(null);
         $this->urlShortener = $urlShortener;
+        $this->translator = $translator;
+        parent::__construct(null);
     }
 
     public function configure()
     {
         $this->setName('shortcode:parse')
-             ->setDescription('Returns the long URL behind a short code')
-             ->addArgument('shortCode', InputArgument::REQUIRED, 'The short code to parse');
+             ->setDescription($this->translator->translate('Returns the long URL behind a short code'))
+             ->addArgument(
+                 'shortCode',
+                 InputArgument::REQUIRED,
+                 $this->translator->translate('The short code to parse')
+             );
     }
 
     public function interact(InputInterface $input, OutputInterface $output)
@@ -47,9 +58,10 @@ class ResolveUrlCommand extends Command
 
         /** @var QuestionHelper $helper */
         $helper = $this->getHelper('question');
-        $question = new Question(
-            '<question>A short code was not provided. Which short code do you want to parse?:</question> '
-        );
+        $question = new Question(sprintf(
+            '<question>%s</question> ',
+            $this->translator->translate('A short code was not provided. Which short code do you want to parse?:')
+        ));
 
         $shortCode = $helper->ask($input, $output, $question);
         if (! empty($shortCode)) {
@@ -64,15 +76,18 @@ class ResolveUrlCommand extends Command
         try {
             $longUrl = $this->urlShortener->shortCodeToUrl($shortCode);
             if (! isset($longUrl)) {
-                $output->writeln(sprintf('<error>No URL found for short code "%s"</error>', $shortCode));
+                $output->writeln(sprintf(
+                    '<error>' . $this->translator->translate('No URL found for short code "%s"') . '</error>',
+                    $shortCode
+                ));
                 return;
             }
 
-            $output->writeln(sprintf('Long URL <info>%s</info>', $longUrl));
+            $output->writeln(sprintf('%s <info>%s</info>', $this->translator->translate('Long URL:'), $longUrl));
         } catch (InvalidShortCodeException $e) {
-            $output->writeln(
-                sprintf('<error>Provided short code "%s" has an invalid format.</error>', $shortCode)
-            );
+            $output->writeln(sprintf('<error>' . $this->translator->translate(
+                'Provided short code "%s" has an invalid format.'
+            ) . '</error>', $shortCode));
         }
     }
 }
diff --git a/module/Common/config/middleware-pipeline.config.php b/module/Common/config/middleware-pipeline.config.php
new file mode 100644
index 00000000..361621c6
--- /dev/null
+++ b/module/Common/config/middleware-pipeline.config.php
@@ -0,0 +1,14 @@
+<?php
+use Shlinkio\Shlink\Common\Middleware;
+
+return [
+
+    'middleware_pipeline' => [
+        'pre-routing' => [
+            'middleware' => [
+                Middleware\LocaleMiddleware::class,
+            ],
+            'priority' => 5,
+        ],
+    ],
+];
diff --git a/module/Common/config/services.config.php b/module/Common/config/services.config.php
index 838b7896..42d9dbc5 100644
--- a/module/Common/config/services.config.php
+++ b/module/Common/config/services.config.php
@@ -4,7 +4,11 @@ use Doctrine\Common\Cache\Cache;
 use Doctrine\ORM\EntityManager;
 use Shlinkio\Shlink\Common\Factory\CacheFactory;
 use Shlinkio\Shlink\Common\Factory\EntityManagerFactory;
+use Shlinkio\Shlink\Common\Factory\TranslatorFactory;
+use Shlinkio\Shlink\Common\Middleware\LocaleMiddleware;
 use Shlinkio\Shlink\Common\Service\IpLocationResolver;
+use Shlinkio\Shlink\Common\Twig\Extension\TranslatorExtension;
+use Zend\I18n\Translator\Translator;
 use Zend\ServiceManager\Factory\InvokableFactory;
 
 return [
@@ -15,10 +19,14 @@ return [
             GuzzleHttp\Client::class => InvokableFactory::class,
             Cache::class => CacheFactory::class,
             IpLocationResolver::class => AnnotatedFactory::class,
+            Translator::class => TranslatorFactory::class,
+            TranslatorExtension::class => AnnotatedFactory::class,
+            LocaleMiddleware::class => AnnotatedFactory::class,
         ],
         'aliases' => [
             'em' => EntityManager::class,
             'httpClient' => GuzzleHttp\Client::class,
+            'translator' => Translator::class,
             AnnotatedFactory::CACHE_SERVICE => Cache::class,
         ],
     ],
diff --git a/module/Common/config/templates.config.php b/module/Common/config/templates.config.php
new file mode 100644
index 00000000..903c1e8c
--- /dev/null
+++ b/module/Common/config/templates.config.php
@@ -0,0 +1,12 @@
+<?php
+use Shlinkio\Shlink\Common\Twig\Extension\TranslatorExtension;
+
+return [
+
+    'twig' => [
+        'extensions' => [
+            TranslatorExtension::class,
+        ],
+    ],
+
+];
diff --git a/module/Common/src/Factory/TranslatorFactory.php b/module/Common/src/Factory/TranslatorFactory.php
new file mode 100644
index 00000000..e41ba2fc
--- /dev/null
+++ b/module/Common/src/Factory/TranslatorFactory.php
@@ -0,0 +1,30 @@
+<?php
+namespace Shlinkio\Shlink\Common\Factory;
+
+use Interop\Container\ContainerInterface;
+use Interop\Container\Exception\ContainerException;
+use Zend\I18n\Translator\Translator;
+use Zend\ServiceManager\Exception\ServiceNotCreatedException;
+use Zend\ServiceManager\Exception\ServiceNotFoundException;
+use Zend\ServiceManager\Factory\FactoryInterface;
+
+class TranslatorFactory implements FactoryInterface
+{
+    /**
+     * Create an object
+     *
+     * @param  ContainerInterface $container
+     * @param  string $requestedName
+     * @param  null|array $options
+     * @return object
+     * @throws ServiceNotFoundException if unable to resolve the service.
+     * @throws ServiceNotCreatedException if an exception is raised when
+     *     creating a service.
+     * @throws ContainerException if any other error occurs
+     */
+    public function __invoke(ContainerInterface $container, $requestedName, array $options = null)
+    {
+        $config = $container->get('config');
+        return Translator::factory(isset($config['translator']) ? $config['translator'] : []);
+    }
+}
diff --git a/module/Common/src/Middleware/LocaleMiddleware.php b/module/Common/src/Middleware/LocaleMiddleware.php
new file mode 100644
index 00000000..20f796ff
--- /dev/null
+++ b/module/Common/src/Middleware/LocaleMiddleware.php
@@ -0,0 +1,82 @@
+<?php
+namespace Shlinkio\Shlink\Common\Middleware;
+
+use Acelaya\ZsmAnnotatedServices\Annotation\Inject;
+use Psr\Http\Message\ResponseInterface as Response;
+use Psr\Http\Message\ServerRequestInterface as Request;
+use Zend\I18n\Translator\Translator;
+use Zend\Stratigility\MiddlewareInterface;
+
+class LocaleMiddleware implements MiddlewareInterface
+{
+    /**
+     * @var Translator
+     */
+    private $translator;
+
+    /**
+     * LocaleMiddleware constructor.
+     * @param Translator $translator
+     *
+     * @Inject({"translator"})
+     */
+    public function __construct(Translator $translator)
+    {
+        $this->translator = $translator;
+    }
+
+    /**
+     * Process an incoming request and/or response.
+     *
+     * Accepts a server-side request and a response instance, and does
+     * something with them.
+     *
+     * If the response is not complete and/or further processing would not
+     * interfere with the work done in the middleware, or if the middleware
+     * wants to delegate to another process, it can use the `$out` callable
+     * if present.
+     *
+     * If the middleware does not return a value, execution of the current
+     * request is considered complete, and the response instance provided will
+     * be considered the response to return.
+     *
+     * Alternately, the middleware may return a response instance.
+     *
+     * Often, middleware will `return $out();`, with the assumption that a
+     * later middleware will return a response.
+     *
+     * @param Request $request
+     * @param Response $response
+     * @param null|callable $out
+     * @return null|Response
+     */
+    public function __invoke(Request $request, Response $response, callable $out = null)
+    {
+        if (! $request->hasHeader('Accept-Language')) {
+            return $out($request, $response);
+        }
+
+        $locale = $request->getHeaderLine('Accept-Language');
+        $this->translator->setLocale($this->normalizeLocale($locale));
+        return $out($request, $response);
+    }
+
+    /**
+     * @param string $locale
+     * @return string
+     */
+    protected function normalizeLocale($locale)
+    {
+        $parts = explode('_', $locale);
+        if (count($parts) > 1) {
+            return $parts[0];
+        }
+
+        $parts = explode('-', $locale);
+        if (count($parts) > 1) {
+            return $parts[0];
+        }
+
+        return $locale;
+    }
+}
diff --git a/module/Common/src/Twig/Extension/TranslatorExtension.php b/module/Common/src/Twig/Extension/TranslatorExtension.php
new file mode 100644
index 00000000..48ee3f11
--- /dev/null
+++ b/module/Common/src/Twig/Extension/TranslatorExtension.php
@@ -0,0 +1,75 @@
+<?php
+namespace Shlinkio\Shlink\Common\Twig\Extension;
+
+use Acelaya\ZsmAnnotatedServices\Annotation\Inject;
+use Zend\I18n\Translator\TranslatorInterface;
+
+class TranslatorExtension extends \Twig_Extension implements TranslatorInterface
+{
+    /**
+     * @var TranslatorInterface
+     */
+    private $translator;
+
+    /**
+     * TranslatorExtension constructor.
+     * @param TranslatorInterface $translator
+     *
+     * @Inject({"translator"})
+     */
+    public function __construct(TranslatorInterface $translator)
+    {
+        $this->translator = $translator;
+    }
+
+    /**
+     * Returns the name of the extension.
+     *
+     * @return string The extension name
+     */
+    public function getName()
+    {
+        return __CLASS__;
+    }
+
+    public function getFunctions()
+    {
+        return [
+            new \Twig_SimpleFunction('translate', [$this, 'translate']),
+            new \Twig_SimpleFunction('translate_plural', [$this, 'translatePlural']),
+        ];
+    }
+
+    /**
+     * Translate a message.
+     *
+     * @param  string $message
+     * @param  string $textDomain
+     * @param  string $locale
+     * @return string
+     */
+    public function translate($message, $textDomain = 'default', $locale = null)
+    {
+        return $this->translator->translate($message, $textDomain, $locale);
+    }
+
+    /**
+     * Translate a plural message.
+     *
+     * @param  string $singular
+     * @param  string $plural
+     * @param  int $number
+     * @param  string $textDomain
+     * @param  string|null $locale
+     * @return string
+     */
+    public function translatePlural(
+        $singular,
+        $plural,
+        $number,
+        $textDomain = 'default',
+        $locale = null
+    ) {
+        $this->translator->translatePlural($singular, $plural, $number, $textDomain, $locale);
+    }
+}
diff --git a/module/Core/config/translator.config.php b/module/Core/config/translator.config.php
new file mode 100644
index 00000000..ae120db3
--- /dev/null
+++ b/module/Core/config/translator.config.php
@@ -0,0 +1,14 @@
+<?php
+return [
+
+    'translator' => [
+        'translation_file_patterns' => [
+            [
+                'type' => 'gettext',
+                'base_dir' => __DIR__ . '/../lang',
+                'pattern' => '%s.mo',
+            ],
+        ],
+    ],
+
+];
diff --git a/module/Core/lang/es.mo b/module/Core/lang/es.mo
new file mode 100644
index 00000000..d34bb83b
Binary files /dev/null and b/module/Core/lang/es.mo differ
diff --git a/module/Core/lang/es.po b/module/Core/lang/es.po
new file mode 100644
index 00000000..3393f072
--- /dev/null
+++ b/module/Core/lang/es.po
@@ -0,0 +1,35 @@
+msgid ""
+msgstr ""
+"Project-Id-Version: Shlink 1.0\n"
+"POT-Creation-Date: 2016-07-21 16:50+0200\n"
+"PO-Revision-Date: 2016-07-21 16:51+0200\n"
+"Last-Translator: \n"
+"Language-Team: \n"
+"Language: es_ES\n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+"X-Generator: Poedit 1.8.7.1\n"
+"X-Poedit-Basepath: ..\n"
+"Plural-Forms: nplurals=2; plural=(n != 1);\n"
+"X-Poedit-SourceCharset: UTF-8\n"
+"X-Poedit-KeywordsList: translate;translaePlural;translate_plural\n"
+"X-Poedit-SearchPath-0: templates\n"
+"X-Poedit-SearchPath-1: config\n"
+"X-Poedit-SearchPath-2: src\n"
+
+msgid "Make sure you included all the characters, with no extra punctuation."
+msgstr "Asegúrate de haber incluído todos los caracteres, sin puntuación extra."
+
+msgid "Oops!"
+msgstr "¡Vaya!"
+
+msgid "This short URL doesn't seem to be valid."
+msgstr "Esta URL acortada no parece ser válida."
+
+msgid "URL Not Found"
+msgstr "URL no encontrada"
+
+#, php-format
+msgid "We encountered a %s %s error."
+msgstr "Hemos encontrado un error %s %s."
diff --git a/module/Core/templates/core/error/404.html.twig b/module/Core/templates/core/error/404.html.twig
index 0c28f29d..fe36f047 100644
--- a/module/Core/templates/core/error/404.html.twig
+++ b/module/Core/templates/core/error/404.html.twig
@@ -1,6 +1,6 @@
 {% extends 'core/layout/default.html.twig' %}
 
-{% block title %}URL Not Found{% endblock %}
+{% block title %}{{ translate('URL Not Found') }}{% endblock %}
 
 {% block stylesheets %}
     <style>
@@ -10,8 +10,8 @@
 {% endblock %}
 
 {% block content %}
-    <h1>Oops!</h1>
+    <h1>{{ translate('Oops!') }}</h1>
     <hr>
-    <p>This short URL doesn't seem to be valid.</p>
-    <p>Make sure you included all the characters, with no extra punctuation.</p>
+    <p>{{ translate('This short URL doesn\'t seem to be valid.') }}</p>
+    <p>{{ translate('Make sure you included all the characters, with no extra punctuation.') }}</p>
 {% endblock %}
diff --git a/module/Core/templates/core/error/error.html.twig b/module/Core/templates/core/error/error.html.twig
index c93b3b7e..7426a33a 100644
--- a/module/Core/templates/core/error/error.html.twig
+++ b/module/Core/templates/core/error/error.html.twig
@@ -10,11 +10,11 @@
 {% endblock %}
 
 {% block content %}
-    <h1>Oops!</h1>
+    <h1>{{ translate('Oops!') }}</h1>
     <hr>
-    <p>We encountered a {{ status }} {{ reason }} error.</p>
+    <p>{{ translate('We encountered a %s %s error.') | format(status, reason) }}</p>
     {% if status == 404 %}
-        <p>This short URL doesn't seem to be valid.</p>
-        <p>Make sure you included all the characters, with no extra punctuation.</p>
+        <p>{{ translate('This short URL doesn\'t seem to be valid.') }}</p>
+        <p>{{ translate('Make sure you included all the characters, with no extra punctuation.') }}</p>
     {% endif %}
 {% endblock %}
diff --git a/module/Rest/config/translator.config.php b/module/Rest/config/translator.config.php
new file mode 100644
index 00000000..ae120db3
--- /dev/null
+++ b/module/Rest/config/translator.config.php
@@ -0,0 +1,14 @@
+<?php
+return [
+
+    'translator' => [
+        'translation_file_patterns' => [
+            [
+                'type' => 'gettext',
+                'base_dir' => __DIR__ . '/../lang',
+                'pattern' => '%s.mo',
+            ],
+        ],
+    ],
+
+];
diff --git a/module/Rest/lang/es.mo b/module/Rest/lang/es.mo
new file mode 100644
index 00000000..2a8d4431
Binary files /dev/null and b/module/Rest/lang/es.mo differ
diff --git a/module/Rest/lang/es.po b/module/Rest/lang/es.po
new file mode 100644
index 00000000..fdfb2ed5
--- /dev/null
+++ b/module/Rest/lang/es.po
@@ -0,0 +1,60 @@
+msgid ""
+msgstr ""
+"Project-Id-Version: Shlink 1.0\n"
+"POT-Creation-Date: 2016-07-21 16:39+0200\n"
+"PO-Revision-Date: 2016-07-21 16:40+0200\n"
+"Last-Translator: \n"
+"Language-Team: \n"
+"Language: es_ES\n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+"X-Generator: Poedit 1.8.7.1\n"
+"X-Poedit-Basepath: ..\n"
+"Plural-Forms: nplurals=2; plural=(n != 1);\n"
+"X-Poedit-SourceCharset: UTF-8\n"
+"X-Poedit-KeywordsList: translate;translatePlural\n"
+"X-Poedit-SearchPath-0: config\n"
+"X-Poedit-SearchPath-1: src\n"
+
+msgid "You have to provide both \"username\" and \"password\""
+msgstr "Debes proporcionar tanto \"username\" como \"password\""
+
+msgid "Invalid username and/or password"
+msgstr "Usuario y/o contraseña no válidos"
+
+msgid "A URL was not provided"
+msgstr "No se ha proporcionado una URL"
+
+#, php-format
+msgid "Provided URL \"%s\" is invalid. Try with a different one."
+msgstr ""
+"La URL \"%s\" proporcionada es inválida. Inténtalo de nuevo con una "
+"diferente."
+
+msgid "Unexpected error occurred"
+msgstr "Ocurrió un error inesperado"
+
+#, php-format
+msgid "Provided short code \"%s\" is invalid"
+msgstr "El código corto \"%s\" proporcionado es inválido"
+
+#, php-format
+msgid "No URL found for shortcode \"%s\""
+msgstr "No se ha encontrado una URL para el código corto \"%s\""
+
+#, php-format
+msgid "Provided short code \"%s\" has an invalid format"
+msgstr "El código corto proporcionado \"%s\" tiene un formato no inválido"
+
+#, php-format
+msgid ""
+"Missing or invalid auth token provided. Perform a new authentication request "
+"and send provided token on every new request on the \"%s\" header"
+msgstr ""
+"No se ha proporcionado token de autenticación o este es inválido. Realia una "
+"nueva petición de autenticación y envía el token proporcionado en cada nueva "
+"petición en la cabecera \"%s\""
+
+#~ msgid "RestToken not found for token \"%s\""
+#~ msgstr "No se ha encontrado un RestToken para el token \"%s\""
diff --git a/module/Rest/src/Action/AuthenticateMiddleware.php b/module/Rest/src/Action/AuthenticateMiddleware.php
index cbea1360..1a37ea90 100644
--- a/module/Rest/src/Action/AuthenticateMiddleware.php
+++ b/module/Rest/src/Action/AuthenticateMiddleware.php
@@ -9,6 +9,7 @@ use Shlinkio\Shlink\Rest\Service\RestTokenService;
 use Shlinkio\Shlink\Rest\Service\RestTokenServiceInterface;
 use Shlinkio\Shlink\Rest\Util\RestUtils;
 use Zend\Diactoros\Response\JsonResponse;
+use Zend\I18n\Translator\TranslatorInterface;
 
 class AuthenticateMiddleware extends AbstractRestMiddleware
 {
@@ -16,16 +17,22 @@ class AuthenticateMiddleware extends AbstractRestMiddleware
      * @var RestTokenServiceInterface
      */
     private $restTokenService;
+    /**
+     * @var TranslatorInterface
+     */
+    private $translator;
 
     /**
      * AuthenticateMiddleware constructor.
      * @param RestTokenServiceInterface|RestTokenService $restTokenService
+     * @param TranslatorInterface $translator
      *
-     * @Inject({RestTokenService::class})
+     * @Inject({RestTokenService::class, "translator"})
      */
-    public function __construct(RestTokenServiceInterface $restTokenService)
+    public function __construct(RestTokenServiceInterface $restTokenService, TranslatorInterface $translator)
     {
         $this->restTokenService = $restTokenService;
+        $this->translator = $translator;
     }
 
     /**
@@ -40,7 +47,7 @@ class AuthenticateMiddleware extends AbstractRestMiddleware
         if (! isset($authData['username'], $authData['password'])) {
             return new JsonResponse([
                 'error' => RestUtils::INVALID_ARGUMENT_ERROR,
-                'message' => 'You have to provide both "username" and "password"'
+                'message' => $this->translator->translate('You have to provide both "username" and "password"'),
             ], 400);
         }
 
@@ -50,7 +57,7 @@ class AuthenticateMiddleware extends AbstractRestMiddleware
         } catch (AuthenticationException $e) {
             return new JsonResponse([
                 'error' => RestUtils::getRestErrorCodeFromException($e),
-                'message' => 'Invalid username and/or password',
+                'message' => $this->translator->translate('Invalid username and/or password'),
             ], 401);
         }
     }
diff --git a/module/Rest/src/Action/CreateShortcodeMiddleware.php b/module/Rest/src/Action/CreateShortcodeMiddleware.php
index fdb0ade3..fe3074fa 100644
--- a/module/Rest/src/Action/CreateShortcodeMiddleware.php
+++ b/module/Rest/src/Action/CreateShortcodeMiddleware.php
@@ -10,6 +10,7 @@ use Shlinkio\Shlink\Core\Service\UrlShortenerInterface;
 use Shlinkio\Shlink\Rest\Util\RestUtils;
 use Zend\Diactoros\Response\JsonResponse;
 use Zend\Diactoros\Uri;
+use Zend\I18n\Translator\TranslatorInterface;
 
 class CreateShortcodeMiddleware extends AbstractRestMiddleware
 {
@@ -21,18 +22,27 @@ class CreateShortcodeMiddleware extends AbstractRestMiddleware
      * @var array
      */
     private $domainConfig;
+    /**
+     * @var TranslatorInterface
+     */
+    private $translator;
 
     /**
      * GenerateShortcodeMiddleware constructor.
      *
      * @param UrlShortenerInterface|UrlShortener $urlShortener
+     * @param TranslatorInterface $translator
      * @param array $domainConfig
      *
-     * @Inject({UrlShortener::class, "config.url_shortener.domain"})
+     * @Inject({UrlShortener::class, "translator", "config.url_shortener.domain"})
      */
-    public function __construct(UrlShortenerInterface $urlShortener, array $domainConfig)
-    {
+    public function __construct(
+        UrlShortenerInterface $urlShortener,
+        TranslatorInterface $translator,
+        array $domainConfig
+    ) {
         $this->urlShortener = $urlShortener;
+        $this->translator = $translator;
         $this->domainConfig = $domainConfig;
     }
 
@@ -48,7 +58,7 @@ class CreateShortcodeMiddleware extends AbstractRestMiddleware
         if (! isset($postData['longUrl'])) {
             return new JsonResponse([
                 'error' => RestUtils::INVALID_ARGUMENT_ERROR,
-                'message' => 'A URL was not provided',
+                'message' => $this->translator->translate('A URL was not provided'),
             ], 400);
         }
         $longUrl = $postData['longUrl'];
@@ -67,12 +77,15 @@ class CreateShortcodeMiddleware extends AbstractRestMiddleware
         } catch (InvalidUrlException $e) {
             return new JsonResponse([
                 'error' => RestUtils::getRestErrorCodeFromException($e),
-                'message' => sprintf('Provided URL "%s" is invalid. Try with a different one.', $longUrl),
+                'message' => sprintf(
+                    $this->translator->translate('Provided URL "%s" is invalid. Try with a different one.'),
+                    $longUrl
+                ),
             ], 400);
         } catch (\Exception $e) {
             return new JsonResponse([
                 'error' => RestUtils::UNKNOWN_ERROR,
-                'message' => 'Unexpected error occured',
+                'message' => $this->translator->translate('Unexpected error occurred'),
             ], 500);
         }
     }
diff --git a/module/Rest/src/Action/GetVisitsMiddleware.php b/module/Rest/src/Action/GetVisitsMiddleware.php
index 3e5bfbaf..75765389 100644
--- a/module/Rest/src/Action/GetVisitsMiddleware.php
+++ b/module/Rest/src/Action/GetVisitsMiddleware.php
@@ -10,6 +10,7 @@ use Shlinkio\Shlink\Core\Service\VisitsTracker;
 use Shlinkio\Shlink\Core\Service\VisitsTrackerInterface;
 use Shlinkio\Shlink\Rest\Util\RestUtils;
 use Zend\Diactoros\Response\JsonResponse;
+use Zend\I18n\Translator\TranslatorInterface;
 
 class GetVisitsMiddleware extends AbstractRestMiddleware
 {
@@ -17,16 +18,22 @@ class GetVisitsMiddleware extends AbstractRestMiddleware
      * @var VisitsTrackerInterface
      */
     private $visitsTracker;
+    /**
+     * @var TranslatorInterface
+     */
+    private $translator;
 
     /**
      * GetVisitsMiddleware constructor.
      * @param VisitsTrackerInterface|VisitsTracker $visitsTracker
+     * @param TranslatorInterface $translator
      *
-     * @Inject({VisitsTracker::class})
+     * @Inject({VisitsTracker::class, "translator"})
      */
-    public function __construct(VisitsTrackerInterface $visitsTracker)
+    public function __construct(VisitsTrackerInterface $visitsTracker, TranslatorInterface $translator)
     {
         $this->visitsTracker = $visitsTracker;
+        $this->translator = $translator;
     }
 
     /**
@@ -52,12 +59,12 @@ class GetVisitsMiddleware extends AbstractRestMiddleware
         } catch (InvalidArgumentException $e) {
             return new JsonResponse([
                 'error' => RestUtils::getRestErrorCodeFromException($e),
-                'message' => sprintf('Provided short code "%s" is invalid', $shortCode),
+                'message' => sprintf($this->translator->translate('Provided short code "%s" is invalid'), $shortCode),
             ], 400);
         } catch (\Exception $e) {
             return new JsonResponse([
                 'error' => RestUtils::UNKNOWN_ERROR,
-                'message' => 'Unexpected error occured',
+                'message' => $this->translator->translate('Unexpected error occurred'),
             ], 500);
         }
     }
diff --git a/module/Rest/src/Action/ListShortcodesMiddleware.php b/module/Rest/src/Action/ListShortcodesMiddleware.php
index 4361ab89..99b1c718 100644
--- a/module/Rest/src/Action/ListShortcodesMiddleware.php
+++ b/module/Rest/src/Action/ListShortcodesMiddleware.php
@@ -9,6 +9,7 @@ use Shlinkio\Shlink\Core\Service\ShortUrlService;
 use Shlinkio\Shlink\Core\Service\ShortUrlServiceInterface;
 use Shlinkio\Shlink\Rest\Util\RestUtils;
 use Zend\Diactoros\Response\JsonResponse;
+use Zend\I18n\Translator\TranslatorInterface;
 
 class ListShortcodesMiddleware extends AbstractRestMiddleware
 {
@@ -18,16 +19,22 @@ class ListShortcodesMiddleware extends AbstractRestMiddleware
      * @var ShortUrlServiceInterface
      */
     private $shortUrlService;
+    /**
+     * @var TranslatorInterface
+     */
+    private $translator;
 
     /**
      * ListShortcodesMiddleware constructor.
      * @param ShortUrlServiceInterface|ShortUrlService $shortUrlService
+     * @param TranslatorInterface $translator
      *
-     * @Inject({ShortUrlService::class})
+     * @Inject({ShortUrlService::class, "translator"})
      */
-    public function __construct(ShortUrlServiceInterface $shortUrlService)
+    public function __construct(ShortUrlServiceInterface $shortUrlService, TranslatorInterface $translator)
     {
         $this->shortUrlService = $shortUrlService;
+        $this->translator = $translator;
     }
 
     /**
@@ -45,7 +52,7 @@ class ListShortcodesMiddleware extends AbstractRestMiddleware
         } catch (\Exception $e) {
             return new JsonResponse([
                 'error' => RestUtils::UNKNOWN_ERROR,
-                'message' => 'Unexpected error occured',
+                'message' => $this->translator->translate('Unexpected error occurred'),
             ], 500);
         }
     }
diff --git a/module/Rest/src/Action/ResolveUrlMiddleware.php b/module/Rest/src/Action/ResolveUrlMiddleware.php
index 92a1e5c2..db7e5827 100644
--- a/module/Rest/src/Action/ResolveUrlMiddleware.php
+++ b/module/Rest/src/Action/ResolveUrlMiddleware.php
@@ -9,6 +9,7 @@ use Shlinkio\Shlink\Core\Service\UrlShortener;
 use Shlinkio\Shlink\Core\Service\UrlShortenerInterface;
 use Shlinkio\Shlink\Rest\Util\RestUtils;
 use Zend\Diactoros\Response\JsonResponse;
+use Zend\I18n\Translator\TranslatorInterface;
 
 class ResolveUrlMiddleware extends AbstractRestMiddleware
 {
@@ -16,16 +17,22 @@ class ResolveUrlMiddleware extends AbstractRestMiddleware
      * @var UrlShortenerInterface
      */
     private $urlShortener;
+    /**
+     * @var TranslatorInterface
+     */
+    private $translator;
 
     /**
      * ResolveUrlMiddleware constructor.
      * @param UrlShortenerInterface|UrlShortener $urlShortener
+     * @param TranslatorInterface $translator
      *
-     * @Inject({UrlShortener::class})
+     * @Inject({UrlShortener::class, "translator"})
      */
-    public function __construct(UrlShortenerInterface $urlShortener)
+    public function __construct(UrlShortenerInterface $urlShortener, TranslatorInterface $translator)
     {
         $this->urlShortener = $urlShortener;
+        $this->translator = $translator;
     }
 
     /**
@@ -43,7 +50,7 @@ class ResolveUrlMiddleware extends AbstractRestMiddleware
             if (! isset($longUrl)) {
                 return new JsonResponse([
                     'error' => RestUtils::INVALID_ARGUMENT_ERROR,
-                    'message' => sprintf('No URL found for shortcode "%s"', $shortCode),
+                    'message' => sprintf($this->translator->translate('No URL found for shortcode "%s"'), $shortCode),
                 ], 400);
             }
 
@@ -53,12 +60,15 @@ class ResolveUrlMiddleware extends AbstractRestMiddleware
         } catch (InvalidShortCodeException $e) {
             return new JsonResponse([
                 'error' => RestUtils::getRestErrorCodeFromException($e),
-                'message' => sprintf('Provided short code "%s" has an invalid format', $shortCode),
+                'message' => sprintf(
+                    $this->translator->translate('Provided short code "%s" has an invalid format'),
+                    $shortCode
+                ),
             ], 400);
         } catch (\Exception $e) {
             return new JsonResponse([
                 'error' => RestUtils::UNKNOWN_ERROR,
-                'message' => 'Unexpected error occured',
+                'message' => $this->translator->translate('Unexpected error occurred'),
             ], 500);
         }
     }
diff --git a/module/Rest/src/Middleware/CheckAuthenticationMiddleware.php b/module/Rest/src/Middleware/CheckAuthenticationMiddleware.php
index 9120e2c6..f05c1b78 100644
--- a/module/Rest/src/Middleware/CheckAuthenticationMiddleware.php
+++ b/module/Rest/src/Middleware/CheckAuthenticationMiddleware.php
@@ -10,6 +10,7 @@ use Shlinkio\Shlink\Rest\Service\RestTokenServiceInterface;
 use Shlinkio\Shlink\Rest\Util\RestUtils;
 use Zend\Diactoros\Response\JsonResponse;
 use Zend\Expressive\Router\RouteResult;
+use Zend\I18n\Translator\TranslatorInterface;
 use Zend\Stratigility\MiddlewareInterface;
 
 class CheckAuthenticationMiddleware implements MiddlewareInterface
@@ -20,16 +21,22 @@ class CheckAuthenticationMiddleware implements MiddlewareInterface
      * @var RestTokenServiceInterface
      */
     private $restTokenService;
+    /**
+     * @var TranslatorInterface
+     */
+    private $translator;
 
     /**
      * CheckAuthenticationMiddleware constructor.
      * @param RestTokenServiceInterface|RestTokenService $restTokenService
+     * @param TranslatorInterface $translator
      *
-     * @Inject({RestTokenService::class})
+     * @Inject({RestTokenService::class, "translator"})
      */
-    public function __construct(RestTokenServiceInterface $restTokenService)
+    public function __construct(RestTokenServiceInterface $restTokenService, TranslatorInterface $translator)
     {
         $this->restTokenService = $restTokenService;
+        $this->translator = $translator;
     }
 
     /**
@@ -93,8 +100,10 @@ class CheckAuthenticationMiddleware implements MiddlewareInterface
         return new JsonResponse([
             'error' => RestUtils::INVALID_AUTH_TOKEN_ERROR,
             'message' => sprintf(
-                'Missing or invalid auth token provided. Perform a new authentication request and send provided token '
-                . 'on every new request on the "%s" header',
+                $this->translator->translate(
+                    'Missing or invalid auth token provided. Perform a new authentication request and send provided '
+                    . 'token on every new request on the "%s" header'
+                ),
                 self::AUTH_TOKEN_HEADER
             ),
         ], 401);
diff --git a/module/Rest/src/Service/RestTokenService.php b/module/Rest/src/Service/RestTokenService.php
index c452af2a..b9dd4a9d 100644
--- a/module/Rest/src/Service/RestTokenService.php
+++ b/module/Rest/src/Service/RestTokenService.php
@@ -21,8 +21,8 @@ class RestTokenService implements RestTokenServiceInterface
     /**
      * ShortUrlService constructor.
      * @param EntityManagerInterface $em
-     *
      * @param array $restConfig
+     *
      * @Inject({"em", "config.rest"})
      */
     public function __construct(EntityManagerInterface $em, array $restConfig)
diff --git a/module/Rest/src/Util/RestUtils.php b/module/Rest/src/Util/RestUtils.php
index 82082dcd..8e50a1cf 100644
--- a/module/Rest/src/Util/RestUtils.php
+++ b/module/Rest/src/Util/RestUtils.php
@@ -21,7 +21,7 @@ class RestUtils
                 return self::INVALID_SHORTCODE_ERROR;
             case $e instanceof Core\InvalidUrlException:
                 return self::INVALID_URL_ERROR;
-            case $e instanceof Core\InvalidArgumentException:
+            case $e instanceof Common\InvalidArgumentException:
                 return self::INVALID_ARGUMENT_ERROR;
             case $e instanceof Rest\AuthenticationException:
                 return self::INVALID_CREDENTIALS_ERROR;