diff --git a/Changes b/Changes
index 82b19fc5..25c78927 100644
--- a/Changes
+++ b/Changes
@@ -2,6 +2,8 @@ Revision history for Perl module Mojo::WebSocketProxy
 
 {{$NEXT}}
     Add warning with transaction details failure, if available.
+    Add optional localization callback
+    Use 'Mojo::JSON' instead of 3rd-party JSON-handling modules
     Don't bother removing args from req storage after SanityCheckFailed.
 
 0.07      2017-08-29 03:04:42 UTC 2017
diff --git a/cpanfile b/cpanfile
index 17f00d50..d883fa9c 100644
--- a/cpanfile
+++ b/cpanfile
@@ -2,8 +2,6 @@ requires 'Class::Method::Modifiers';
 requires 'Data::UUID';
 requires 'Future';
 requires 'Guard';
-requires 'JSON';
-requires 'JSON::XS';
 requires 'MojoX::JSON::RPC';
 requires 'Mojolicious';
 requires 'Scalar::Util';
diff --git a/dist.ini b/dist.ini
index 42a3da6c..1fbe5ae7 100644
--- a/dist.ini
+++ b/dist.ini
@@ -44,6 +44,8 @@ perltidyrc = t/rc/.perltidyrc
 [Test::Compile]
 [Test::Synopsis]
 [Test::EOL]
+finder = :InstallModules
+finder = :ExecFiles
 [Test::Version]
 [Test::Pod::LinkCheck]
 [PodCoverageTests]
diff --git a/lib/Mojo/WebSocketProxy/CallingEngine.pm b/lib/Mojo/WebSocketProxy/CallingEngine.pm
index 44ffb2e5..36c3f848 100644
--- a/lib/Mojo/WebSocketProxy/CallingEngine.pm
+++ b/lib/Mojo/WebSocketProxy/CallingEngine.pm
@@ -3,9 +3,9 @@ package Mojo::WebSocketProxy::CallingEngine;
 use strict;
 use warnings;
 
+use Mojo::JSON qw(encode_json);
 use MojoX::JSON::RPC::Client;
 use Guard;
-use JSON;
 
 ## VERSION
 
diff --git a/lib/Mojo/WebSocketProxy/Dispatcher.pm b/lib/Mojo/WebSocketProxy/Dispatcher.pm
index 49b998d8..963ea426 100644
--- a/lib/Mojo/WebSocketProxy/Dispatcher.pm
+++ b/lib/Mojo/WebSocketProxy/Dispatcher.pm
@@ -4,13 +4,13 @@ use strict;
 use warnings;
 
 use Mojo::Base 'Mojolicious::Controller';
+use Mojo::JSON qw(encode_json);
 use Mojo::WebSocketProxy::Parser;
 use Mojo::WebSocketProxy::Config;
 use Mojo::WebSocketProxy::CallingEngine;
 
 use Class::Method::Modifiers;
 
-use Mojo::JSON qw(encode_json);
 use Future::Utils qw/fmap/;
 use Scalar::Util qw(blessed);
 use Variable::Disposition qw(dispose retain retain_future);
diff --git a/lib/Mojolicious/Plugin/WebSocketProxy.pm b/lib/Mojolicious/Plugin/WebSocketProxy.pm
index a0a00300..fbd8f075 100644
--- a/lib/Mojolicious/Plugin/WebSocketProxy.pm
+++ b/lib/Mojolicious/Plugin/WebSocketProxy.pm
@@ -14,6 +14,8 @@ sub register {
 
     die 'No base path found!' unless $config->{base_path};
 
+    my $localizer = $config->{localizer} || sub { $_[1] };
+
     my $url_setter;
     $url_setter = delete $config->{url} if $config->{url} and ref($config->{url}) eq 'CODE';
     $app->helper(
@@ -24,12 +26,11 @@ sub register {
         });
     $app->helper(
         wsp_error => sub {
-            shift; # $c
-            my ($msg_type, $code, $message, $details) = @_;
+            my ($c, $msg_type, $code, $message, $details) = @_;
 
             my $error = {
                 code    => $code,
-                message => $message
+                message => $localizer->($c, $message),
             };
             $error->{details} = $details if ref($details) eq 'HASH' && keys %$details;
 
@@ -84,6 +85,10 @@ Mojolicious::Plugin::WebSocketProxy
         my $self = shift;
         $self->plugin(
             'web_socket_proxy' => {
+                localizer => sub {
+                    my ($c, $error) = @_;
+                    return $translate_somehow->($error) // $error;
+                },
                 actions => [
                     ['json_key', {some_param => 'some_value'}]
                 ],
diff --git a/t/05_basic.t b/t/05_basic.t
index 6185e628..1db107f9 100644
--- a/t/05_basic.t
+++ b/t/05_basic.t
@@ -3,8 +3,6 @@
 use strict;
 use warnings;
 
-use JSON;
-
 # Mojolicious app for testing
 package WebsocketProxy;
 
@@ -48,6 +46,7 @@ use Test::More;
 use Test::Mojo;
 use Test::MockModule;
 use Test::MockObject;
+use Mojo::JSON qw(decode_json encode_json);
 
 # Mocking RPC client to catch RPC calls
 my ($url, $call_params, $fake_rpc_response, $fake_rpc_client, $rpc_client_mock, $rpc_response);
diff --git a/t/10-before_forward.t b/t/10-before_forward.t
index 2dd9c76e..a7082fdf 100644
--- a/t/10-before_forward.t
+++ b/t/10-before_forward.t
@@ -4,7 +4,7 @@ use warnings;
 use t::TestWSP qw/test_wsp/;
 use Test::More;
 use Test::Mojo;
-use JSON::XS;
+use Mojo::JSON qw(decode_json encode_json);
 use Mojo::IOLoop;
 use Future;
 
diff --git a/t/11-timeout.t b/t/11-timeout.t
index 355f617c..125fddc5 100644
--- a/t/11-timeout.t
+++ b/t/11-timeout.t
@@ -6,7 +6,7 @@ local $ENV{MOJO_WEBSOCKETPROXY_TIMEOUT} = 1;
 use t::TestWSP qw/test_wsp/;
 use Test::More;
 use Test::Mojo;
-use JSON::XS;
+use Mojo::JSON qw(decode_json encode_json);
 use Mojo::IOLoop;
 use Future;
 
diff --git a/t/12-before_send_api_response.t b/t/12-before_send_api_response.t
index 0e97e6ab..a9762a8a 100644
--- a/t/12-before_send_api_response.t
+++ b/t/12-before_send_api_response.t
@@ -4,7 +4,7 @@ use warnings;
 use t::TestWSP qw/test_wsp/;
 use Test::More;
 use Test::Mojo;
-use JSON::XS;
+use Mojo::JSON qw(decode_json encode_json);
 use Mojo::IOLoop;
 use Future;
 
diff --git a/t/13-action-not-found.t b/t/13-action-not-found.t
index cff0f441..00154924 100644
--- a/t/13-action-not-found.t
+++ b/t/13-action-not-found.t
@@ -4,7 +4,7 @@ use warnings;
 use t::TestWSP qw/test_wsp/;
 use Test::More;
 use Test::Mojo;
-use JSON::XS;
+use Mojo::JSON qw(decode_json encode_json);
 use Mojo::IOLoop;
 use Future;
 
diff --git a/t/14-bad-request.t b/t/14-bad-request.t
index 6c94eafc..9dbbd27a 100644
--- a/t/14-bad-request.t
+++ b/t/14-bad-request.t
@@ -4,7 +4,7 @@ use warnings;
 use t::TestWSP qw/test_wsp/;
 use Test::More;
 use Test::Mojo;
-use JSON::XS;
+use Mojo::JSON qw(decode_json encode_json);
 use Mojo::IOLoop;
 use Future;
 
diff --git a/t/15-simple-success.t b/t/15-simple-success.t
index eea9c1f2..c3e28901 100644
--- a/t/15-simple-success.t
+++ b/t/15-simple-success.t
@@ -4,7 +4,7 @@ use warnings;
 use t::TestWSP qw/test_wsp/;
 use Test::More;
 use Test::Mojo;
-use JSON::XS;
+use Mojo::JSON qw(decode_json encode_json);
 use Mojo::IOLoop;
 use Future;
 
diff --git a/t/16-auth-error-sample.t b/t/16-auth-error-sample.t
index ae2649b8..95a58ff1 100644
--- a/t/16-auth-error-sample.t
+++ b/t/16-auth-error-sample.t
@@ -4,7 +4,7 @@ use warnings;
 use t::TestWSP qw/test_wsp/;
 use Test::More;
 use Test::Mojo;
-use JSON::XS;
+use Mojo::JSON qw(decode_json encode_json);
 use Mojo::IOLoop;
 use Future;
 
diff --git a/t/17-instead_of_forward.t b/t/17-instead_of_forward.t
index 30784fc6..edf7dea0 100644
--- a/t/17-instead_of_forward.t
+++ b/t/17-instead_of_forward.t
@@ -4,7 +4,7 @@ use warnings;
 use t::TestWSP qw/test_wsp/;
 use Test::More;
 use Test::Mojo;
-use JSON::XS;
+use Mojo::JSON qw(decode_json encode_json);
 use Mojo::IOLoop;
 use Future;
 
diff --git a/t/18-per-action_before-forward.t b/t/18-per-action_before-forward.t
index 805e508d..098a36c7 100644
--- a/t/18-per-action_before-forward.t
+++ b/t/18-per-action_before-forward.t
@@ -4,7 +4,7 @@ use warnings;
 use t::TestWSP qw/test_wsp/;
 use Test::More;
 use Test::Mojo;
-use JSON::XS;
+use Mojo::JSON qw(decode_json encode_json);
 use Mojo::IOLoop;
 use Future;
 
diff --git a/t/19-rpc_response_cb.t b/t/19-rpc_response_cb.t
index 0e98292a..1eb3a965 100644
--- a/t/19-rpc_response_cb.t
+++ b/t/19-rpc_response_cb.t
@@ -4,7 +4,7 @@ use warnings;
 use t::TestWSP qw/test_wsp/;
 use Test::More;
 use Test::Mojo;
-use JSON::XS;
+use Mojo::JSON qw(decode_json encode_json);
 use Mojo::IOLoop;
 use Future;
 
diff --git a/t/20-after_got_rpc_response.t b/t/20-after_got_rpc_response.t
index 32ecf08b..dfa9a31e 100644
--- a/t/20-after_got_rpc_response.t
+++ b/t/20-after_got_rpc_response.t
@@ -4,7 +4,7 @@ use warnings;
 use t::TestWSP qw/test_wsp/;
 use Test::More;
 use Test::Mojo;
-use JSON::XS;
+use Mojo::JSON qw(decode_json encode_json);
 use Mojo::IOLoop;
 use Future;
 
diff --git a/t/21-mojo-stash.t b/t/21-mojo-stash.t
index 24920ce2..feced418 100644
--- a/t/21-mojo-stash.t
+++ b/t/21-mojo-stash.t
@@ -4,7 +4,7 @@ use warnings;
 use t::TestWSP qw/test_wsp/;
 use Test::More;
 use Test::Mojo;
-use JSON::XS;
+use Mojo::JSON qw(decode_json encode_json);
 use Mojo::IOLoop;
 use Future;
 
diff --git a/t/22-override-response.t b/t/22-override-response.t
index 6537312d..0739f20b 100644
--- a/t/22-override-response.t
+++ b/t/22-override-response.t
@@ -4,7 +4,7 @@ use warnings;
 use t::TestWSP qw/test_wsp/;
 use Test::More;
 use Test::Mojo;
-use JSON::XS;
+use Mojo::JSON qw(decode_json encode_json);
 use Mojo::IOLoop;
 use Future;
 
diff --git a/t/23-binary-frame.t b/t/23-binary-frame.t
index f1ad1a25..fae06f4b 100644
--- a/t/23-binary-frame.t
+++ b/t/23-binary-frame.t
@@ -4,7 +4,7 @@ use warnings;
 use t::TestWSP qw/test_wsp/;
 use Test::More;
 use Test::Mojo;
-use JSON::XS;
+use Mojo::JSON qw(decode_json encode_json);
 use Mojo::IOLoop;
 use Future;
 use Path::Tiny;
diff --git a/t/24-localize.t b/t/24-localize.t
new file mode 100644
index 00000000..7ca223e2
--- /dev/null
+++ b/t/24-localize.t
@@ -0,0 +1,41 @@
+use strict;
+use warnings;
+
+use t::TestWSP qw/test_wsp/;
+use Test::More;
+use Test::Mojo;
+use Mojo::JSON qw(decode_json encode_json);
+use Mojo::IOLoop;
+use Future;
+
+package t::FrontEnd {
+    use base 'Mojolicious';
+    # does not matter
+    sub startup {
+         my $self = shift;
+         $self->helper('l' => sub {
+            my ($c, $message) = @_;
+            return "[localized] : $message";
+         });
+         $self->plugin(
+             'web_socket_proxy' => {
+                localizer => sub { shift->l(shift) },
+                actions => [
+                    ['success', {stash_params => [qw/lang/]}],
+                ],
+                base_path => '/api',
+                url => $ENV{T_TestWSP_RPC_URL} // die("T_TestWSP_RPC_URL is not defined"),
+             }
+         );
+    }
+};
+
+test_wsp {
+    my ($t) = @_;
+    $t->websocket_ok('/api' => {});
+    $t->send_ok({json => 'invalid', lang => 'ru'})->message_ok;
+    is decode_json($t->message->[1])->{error}->{code}, 'BadRequest';
+    is decode_json($t->message->[1])->{error}->{message}, '[localized] : The application sent an invalid request.';
+} 't::FrontEnd';
+
+done_testing;
diff --git a/t/SampleRPC.pm b/t/SampleRPC.pm
index b1f676b0..30b65f49 100644
--- a/t/SampleRPC.pm
+++ b/t/SampleRPC.pm
@@ -5,7 +5,7 @@ use warnings;
 
 use MojoX::JSON::RPC::Service;
 use Mojo::Base 'Mojolicious';
-use JSON::XS;
+use Mojo::JSON qw(decode_json encode_json);
 
 sub startup {
     my $self = shift;