diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..40a512f
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+/vendor
+/composer.phar
+/composer.lock
diff --git a/composer.json b/composer.json
new file mode 100644
index 0000000..fe392b9
--- /dev/null
+++ b/composer.json
@@ -0,0 +1,28 @@
+{
+  "name": "bjoern-buettner/dependency-injector",
+  "description": "description",
+  "license": "MIT",
+  "authors": [
+    {
+      "name": "Björn Büttner",
+      "email": "email@example.com"
+    }
+  ],
+  "require": {
+    "php": "^8.1",
+    "symfony/string": "^6.3"
+  },
+  "require-dev": {
+    "phpunit/phpunit": "^9.5"
+  },
+  "autoload": {
+    "psr-4": {
+      "Me\\BjoernBuettner\\DependencyInjector\\": "src/"
+    }
+  },
+  "autoload-dev": {
+    "psr-4": {
+      "Me\\BjoernBuettner\\DependencyInjector\\": "test/"
+    }
+  }
+}
\ No newline at end of file
diff --git a/src/DependencyBuilder.php b/src/DependencyBuilder.php
new file mode 100644
index 0000000..94d2953
--- /dev/null
+++ b/src/DependencyBuilder.php
@@ -0,0 +1,106 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Me\BjoernBuettner\DependencyInjector;
+
+use ReflectionClass;
+use ReflectionException;
+use ReflectionMethod;
+use ReflectionParameter;
+use RuntimeException;
+use Symfony\Component\String\UnicodeString;
+
+class DependencyBuilder
+{
+    /**
+     * @var array<string, object>
+     */
+    private array $cache = [];
+
+    /**
+     * @param array<string, mixed> $params
+     * @param array<string, string> $interfaces
+     * @param array<string, string> $factories
+     */
+    public function __construct(
+        private readonly array $params = [],
+        private readonly array $interfaces = [],
+        private readonly array $factories = [],
+    ) {
+    }
+
+    /**
+     * @throws ReflectionException
+     */
+    private function getParamValue(ReflectionParameter $param, array $variables, string $key): mixed
+    {
+        if (isset($variables[$key])) {
+            return $variables[$key];
+        }
+        if ($type = $param->getType()) {
+            if (!$type->isBuiltin()) {
+                return $this->build($type->getName());
+            }
+            $envName = (new UnicodeString($param->getName()))->snake()->upper()->toString();
+            if (isset($_ENV[$envName])) {
+                return match ($param->getType()->getName()) {
+                    'int' => (int)$_ENV[$envName],
+                    'float' => (float)$_ENV[$envName],
+                    'bool' => $_ENV[$envName] === 'true',
+                    'array' => explode(',', $_ENV[$envName]),
+                    default => (string)$_ENV[$envName],
+                };
+            }
+            if ($type->allowsNull()) {
+                return null;
+            }
+        }
+        if ($param->isDefaultValueAvailable()) {
+            return $param->getDefaultValue();
+        }
+        throw new UnresolvableParameter("Cannot resolve parameter {$param->getName()}.");
+    }
+    /**
+     * @throws ReflectionException
+     */
+    public function build(string $class): object
+    {
+        if (isset($this->cache[$class])) {
+            return $this->cache[$class];
+        }
+        if (isset($this->factories[$class])) {
+            return $this->cache[$class] = $this->build($this->factories[$class])->get();
+        }
+        if (isset($this->interfaces[$class])) {
+            return $this->cache[$class] = $this->build($this->interfaces[$class]);
+        }
+        $rc = new ReflectionClass($class);
+        $constructor = $rc->getConstructor();
+        if (!$constructor) {
+            return $this->cache[$class] = $rc->newInstance();
+        }
+        $params = $constructor->getParameters();
+        $args = [];
+        foreach ($params as $param) {
+            $args[] = $this->getParamValue($param, $this->params, $class . '.' . $param->getName());
+        }
+        return $this->cache[$class] = $rc->newInstanceArgs($args);
+    }
+
+    /**
+     * @param array<string, string> $variables
+     * @throws ReflectionException
+     */
+    public function call(string $class, string $method, array $variables = []): string
+    {
+        $object = $this->build($class);
+        $rm = new ReflectionMethod($object, $method);
+        $params = $rm->getParameters();
+        $args = [];
+        foreach ($params as $param) {
+            $args[] = $this->getParamValue($param, $variables, $param->getName());
+        }
+        return $rm->invokeArgs($object, $args);
+    }
+}
diff --git a/src/UnresolvableParameter.php b/src/UnresolvableParameter.php
new file mode 100644
index 0000000..3dd0144
--- /dev/null
+++ b/src/UnresolvableParameter.php
@@ -0,0 +1,10 @@
+<?php
+declare(strict_types=1);
+
+namespace Me\BjoernBuettner\DependencyInjector;
+
+use UnexpectedValueException;
+
+class UnresolvableParameter extends UnexpectedValueException
+{
+}
\ No newline at end of file
diff --git a/test/DependencyBuilderTest.php b/test/DependencyBuilderTest.php
new file mode 100644
index 0000000..f45a864
--- /dev/null
+++ b/test/DependencyBuilderTest.php
@@ -0,0 +1,10 @@
+<?php
+declare(strict_types=1);
+
+namespace Me\BjoernBuettner\DependencyInjector;
+
+use PHPUnit\Framework\TestCase;
+
+class DependencyBuilderTest extends TestCase
+{
+}