diff --git a/config/services.yml b/config/services.yml
index afd00b9..75f8706 100644
--- a/config/services.yml
+++ b/config/services.yml
@@ -3,6 +3,9 @@ services:
     class: Symfony\Component\Console\Application
     autowire: true
 
+  app.builder:
+    class: Opdavies\GmailFilterBuilder\Service\Builder
+
   app.generate.command:
     class: Opdavies\GmailFilterBuilder\Console\Command\GenerateCommand
     autowire: true
diff --git a/src/Console/Command/GenerateCommand.php b/src/Console/Command/GenerateCommand.php
index 70dea4e..05c256e 100644
--- a/src/Console/Command/GenerateCommand.php
+++ b/src/Console/Command/GenerateCommand.php
@@ -7,6 +7,7 @@ use Symfony\Component\Console\Command\Command;
 use Symfony\Component\Console\Input\InputArgument;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Output\OutputInterface;
+use Symfony\Component\Console\Style\SymfonyStyle;
 
 class GenerateCommand extends Command
 {
@@ -43,6 +44,10 @@ class GenerateCommand extends Command
             throw new \Exception('No filters.php file found.');
         }
 
-        echo new Builder($filters);
+        // TOOD: Check return code.
+        new Builder($filters, $outputFile);
+
+        $io = new SymfonyStyle($input, $output);
+        $io->success(sprintf('%s file generated.', $outputFile));
     }
 }
diff --git a/src/Service/Builder.php b/src/Service/Builder.php
index 9ee9e3d..f8cf70f 100644
--- a/src/Service/Builder.php
+++ b/src/Service/Builder.php
@@ -3,17 +3,28 @@
 namespace Opdavies\GmailFilterBuilder\Service;
 
 use Opdavies\GmailFilterBuilder\Filter;
+use Symfony\Component\Filesystem\Filesystem;
 
 class Builder
 {
+    private $filesystem;
+
     /**
      * @var array
      */
     private $filters = [];
 
-    public function __construct(array $filters)
-    {
+    /**
+     * @var
+     */
+    private $outputFile;
+
+    public function __construct(array $filters, $outputFile = 'filters.xml') {
+        $this->filesystem = new Filesystem();
         $this->filters = $filters;
+        $this->outputFile = $outputFile;
+
+        $this->build();
     }
 
     public function __toString()
@@ -35,7 +46,9 @@ class Builder
             return $this->buildEntry($items);
         })->implode(PHP_EOL);
 
-        return collect([$prefix, $xml, $suffix])->implode(PHP_EOL);
+        $content = collect([$prefix, $xml, $suffix])->implode(PHP_EOL);
+
+        $this->filesystem->dumpFile($this->outputFile, $content);
     }
 
     /**