diff --git a/.github/workflows/run-grumphp-test.yml b/.github/workflows/run-grumphp-test.yml
new file mode 100644
index 0000000..d5d7fd9
--- /dev/null
+++ b/.github/workflows/run-grumphp-test.yml
@@ -0,0 +1,18 @@
+name: Run grumphp with different versions
+on: [push]
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        php:
+          - '8.0'
+          - '8.1'
+          - '8.2'
+    container:
+      image: kanti/buildy:${{ matrix.php }}
+    steps:
+      - uses: actions/checkout@v2
+      - run: composer install --no-progress --no-scripts -n
+      - run: ./vendor/bin/grumphp run
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..d1502b0
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+vendor/
+composer.lock
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..cc34782
--- /dev/null
+++ b/README.md
@@ -0,0 +1,19 @@
+# phpstan-git-files
+
+This phpstan extension automatically adds all your `.php` files from git to be checked by phpstan.
+
+## install
+
+`composer req --dev phpstan/extension-installer andersundsehr/phpstan-git-files`
+
+<details>
+  <summary>Manual installation</summary>
+
+If you don't want to use `phpstan/extension-installer`, put this into your phpstan.neon config:
+
+```NEON
+includes:
+    - vendor/andersundsehr/phpstan-git-files/extension.neon
+```
+
+</details>
diff --git a/composer.json b/composer.json
new file mode 100644
index 0000000..ba547ad
--- /dev/null
+++ b/composer.json
@@ -0,0 +1,39 @@
+{
+  "name": "andersundsehr/phpstan-git-files",
+  "description": "Add all git files into phpstan config automatically",
+  "type": "phpstan-extension",
+  "autoload": {
+    "psr-4": {
+      "AUS\\PhpstanGitFiles\\": "src/"
+    }
+  },
+  "authors": [
+    {
+      "name": "Matthias Vogel",
+      "email": "m.vogel@andersundsehr.com"
+    }
+  ],
+  "require": {
+    "phpstan/phpstan": "^1.9",
+    "php": "~8.0 || ~8.1 || ~8.2",
+    "composer-plugin-api" : "^2.1.0"
+  },
+  "config": {
+    "sort-packages": true,
+    "allow-plugins": {
+      "phpro/grumphp": true,
+      "phpstan/extension-installer": true,
+      "pluswerk/grumphp-config": true
+    }
+  },
+  "require-dev": {
+    "pluswerk/grumphp-config": "^6.1"
+  },
+  "extra": {
+    "phpstan": {
+      "includes": [
+        "extension.neon"
+      ]
+    }
+  }
+}
diff --git a/extension.neon b/extension.neon
new file mode 100644
index 0000000..7d7751e
--- /dev/null
+++ b/extension.neon
@@ -0,0 +1,2 @@
+includes:
+  - extension.php
diff --git a/extension.php b/extension.php
new file mode 100644
index 0000000..2399e58
--- /dev/null
+++ b/extension.php
@@ -0,0 +1,9 @@
+<?php
+
+$paths = array_filter(explode("\n", (string)shell_exec("git ls-files | grep '\.php$'")));
+$absolutPaths = array_map(static fn($string) => getcwd() . '/' . $string, $paths);
+return [
+    'parameters' => [
+        'paths' => $absolutPaths,
+    ],
+];
diff --git a/grumphp.yml b/grumphp.yml
new file mode 100644
index 0000000..0c162b1
--- /dev/null
+++ b/grumphp.yml
@@ -0,0 +1,16 @@
+imports:
+  - { resource: vendor/pluswerk/grumphp-config/grumphp.yml }
+parameters:
+  convention.process_timeout: 240
+  convention.security_checker_blocking: true
+  convention.jsonlint_ignore_pattern: {  }
+  convention.xmllint_ignore_pattern: {  }
+  convention.yamllint_ignore_pattern: {  }
+  convention.phpcslint_ignore_pattern: {  }
+  convention.phpcslint_exclude: {  }
+  convention.xlifflint_ignore_pattern: {  }
+  convention.rector_ignore_pattern: {  }
+  convention.rector_enabled: true
+  convention.rector_config: rector.php
+  convention.rector_clear-cache: false
+  convention.phpstan_level: max
diff --git a/phpstan.neon b/phpstan.neon
new file mode 100644
index 0000000..2541c5b
--- /dev/null
+++ b/phpstan.neon
@@ -0,0 +1,5 @@
+includes:
+  - extension.neon
+
+parameters:
+  level: max
diff --git a/rector.php b/rector.php
new file mode 100644
index 0000000..cb9a514
--- /dev/null
+++ b/rector.php
@@ -0,0 +1,46 @@
+<?php
+
+declare(strict_types=1);
+
+use PLUS\GrumPHPConfig\RectorSettings;
+use Rector\Config\RectorConfig;
+use Rector\Caching\ValueObject\Storage\FileCacheStorage;
+
+return static function (RectorConfig $rectorConfig): void {
+    $rectorConfig->parallel();
+    $rectorConfig->importNames();
+    $rectorConfig->importShortClasses();
+    $rectorConfig->cacheClass(FileCacheStorage::class);
+    $rectorConfig->cacheDirectory('./var/cache/rector');
+
+    $rectorConfig->paths(
+        array_filter([
+            is_dir(__DIR__ . '/src') ? __DIR__ . '/src' : null,
+            is_dir(__DIR__ . '/extensions') ? __DIR__ . '/extensions' : null,
+            is_dir(__DIR__ . '/Classes') ? __DIR__ . '/Classes' : null,
+        ])
+    );
+
+    // define sets of rules
+    $rectorConfig->sets(
+        [
+            ...RectorSettings::sets(true),
+            ...RectorSettings::setsTypo3(false),
+        ]
+    );
+
+    // remove some rules
+    // ignore some files
+    $rectorConfig->skip(
+        [
+            ...RectorSettings::skip(),
+            ...RectorSettings::skipTypo3(),
+
+            /**
+             * rector should not touch these files
+             */
+            //__DIR__ . '/src/Example',
+            //__DIR__ . '/src/Example.php',
+        ]
+    );
+};