diff --git a/README.md b/README.md
index 7fd5d13..c2c8991 100644
--- a/README.md
+++ b/README.md
@@ -53,4 +53,12 @@ find_binary
 ```bash
 php find_binary.php <integer>
 ```
-Decompose an integer into powers of two
\ No newline at end of file
+Decompose an integer into powers of two
+
+compare_hashmaps
+----------------
+
+```bash
+php compare_yaml_hashmaps.php file1 file2
+```
+Compare 2 YAML hashmap files (such as symfony parameters.yml files)
\ No newline at end of file
diff --git a/Util/TextColorWriter.php b/Util/TextColorWriter.php
index 529c142..7c30a0a 100644
--- a/Util/TextColorWriter.php
+++ b/Util/TextColorWriter.php
@@ -42,7 +42,7 @@ public static function textColor($string, $colorID)
      *
      * @return array
      */
-    private function getKnownColors()
+    private static function getKnownColors()
     {
         $colors = array(
             static::BASH_PROMPT_BLACK,
diff --git a/compare_yaml_hashmaps.php b/compare_yaml_hashmaps.php
new file mode 100644
index 0000000..c539b3a
--- /dev/null
+++ b/compare_yaml_hashmaps.php
@@ -0,0 +1,88 @@
+<?php
+
+require_once __DIR__.'/vendor/autoload.php';
+
+use Symfony\Component\Yaml\Yaml;
+
+/**
+ * Validate console input
+ *
+ * Die if input is not valid
+ *
+ * @param  array $argv user inputs
+ */
+function validateInput($argv)
+{
+    if (count($argv) !== 4) {
+        echo 'php compare_hashmaps <file1> <file2> <root_node>' . PHP_EOL;
+        die(1);
+    }
+
+    if (!file_exists($argv[1])) {
+        echo "Error: " . $argv[1] . " is not a valid file" . PHP_EOL;
+        die(1);
+    }
+    if (!file_exists($argv[2])) {
+        echo "Error: " . $argv[2] . " is not a valid file" . PHP_EOL;
+        die(1);
+    }
+}
+
+/**
+ * @param string $filepath
+ * @param string $rootNode
+ *
+ * @return array
+ * @throws Exception
+ */
+function extractArrayFromFile($filepath, $rootNode)
+{
+    $value = Yaml::parse(file_get_contents($filepath));
+
+    if (!array_key_exists($rootNode, $value)) {
+        $showKeys = implode(', ', array_keys($value));
+        throw new \RuntimeException("Expects root node '$rootNode'' in file $filepath, got: $showKeys");
+    }
+
+    return $value[$rootNode];
+}
+
+validateInput($argv);
+
+require 'Util/TextColorWriter.php';
+
+$filepath1 = $argv[1];
+$filepath2 = $argv[2];
+$rootNode = $argv[3];
+
+$list1 = extractArrayFromFile(realpath($filepath1), $rootNode);
+$list2 = extractArrayFromFile(realpath($filepath2), $rootNode);
+
+$inFile1ButNotInFile2 = [];
+$inFile2ButNotInFile1 = [];
+
+foreach ($list1 as $key => $value) {
+    if (!array_key_exists($key, $list2)) {
+        $inFile1ButNotInFile2[$key] = $value;
+    }
+}
+foreach ($list2 as $key => $value) {
+    if (!array_key_exists($key, $list1)) {
+        $inFile2ButNotInFile1[$key] = $value;
+    }
+}
+
+
+// echo result
+echo TextColorWriter::textColor('Done', TextColorWriter::BASH_PROMPT_GREEN) . PHP_EOL;
+echo TextColorWriter::textColor('Found in file 1 but not in file 2:', TextColorWriter::BASH_PROMPT_GREEN) . PHP_EOL;
+
+foreach ($inFile1ButNotInFile2 as $key => $value) {
+    echo '   - ' . $key . PHP_EOL;
+}
+
+echo TextColorWriter::textColor('Found in file 2 but not in file 1:', TextColorWriter::BASH_PROMPT_GREEN) . PHP_EOL;
+
+foreach ($inFile2ButNotInFile1 as $key => $value) {
+    echo '   - ' . $key . PHP_EOL;
+}
diff --git a/composer.json b/composer.json
new file mode 100644
index 0000000..010ac70
--- /dev/null
+++ b/composer.json
@@ -0,0 +1,9 @@
+{
+    "name": "matks/php_scripts",
+    "description": "Useful php scripts",
+    "type": "library",
+    "require": {
+        "symfony/yaml": "^3.2"
+    },
+    "license": "MIT"
+}
diff --git a/composer.lock b/composer.lock
new file mode 100644
index 0000000..4a28d03
--- /dev/null
+++ b/composer.lock
@@ -0,0 +1,74 @@
+{
+    "_readme": [
+        "This file locks the dependencies of your project to a known state",
+        "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#composer-lock-the-lock-file",
+        "This file is @generated automatically"
+    ],
+    "hash": "25f22b21561a33adbe36c50e82567d9e",
+    "content-hash": "2ac310c063d671147381ec25a693d9b6",
+    "packages": [
+        {
+            "name": "symfony/yaml",
+            "version": "v3.2.1",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/symfony/yaml.git",
+                "reference": "a7095af4b97a0955f85c8989106c249fa649011f"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/symfony/yaml/zipball/a7095af4b97a0955f85c8989106c249fa649011f",
+                "reference": "a7095af4b97a0955f85c8989106c249fa649011f",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.5.9"
+            },
+            "require-dev": {
+                "symfony/console": "~2.8|~3.0"
+            },
+            "suggest": {
+                "symfony/console": "For validating YAML files using the lint command"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "3.2-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Symfony\\Component\\Yaml\\": ""
+                },
+                "exclude-from-classmap": [
+                    "/Tests/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Fabien Potencier",
+                    "email": "fabien@symfony.com"
+                },
+                {
+                    "name": "Symfony Community",
+                    "homepage": "https://symfony.com/contributors"
+                }
+            ],
+            "description": "Symfony Yaml Component",
+            "homepage": "https://symfony.com",
+            "time": "2016-12-10 10:07:06"
+        }
+    ],
+    "packages-dev": [],
+    "aliases": [],
+    "minimum-stability": "stable",
+    "stability-flags": [],
+    "prefer-stable": false,
+    "prefer-lowest": false,
+    "platform": [],
+    "platform-dev": []
+}