diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..d577305
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+.vscode
+export.json
+export.csv
\ No newline at end of file
diff --git a/README.md b/README.md
index 1e6b398..717522b 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,8 @@
 # psono-json-to-bitwarden-csv
 
-Script to convert psono exports (JSON) to bitwarden import compatible CSV
\ No newline at end of file
+Script to convert psono exports (JSON) to bitwarden import compatible CSV
+
+usage:
+    convert.php export.json
+
+This will export a file called export.csv that you can import into Bitwarden as a generic CSV.
\ No newline at end of file
diff --git a/convert.php b/convert.php
new file mode 100644
index 0000000..c65015c
--- /dev/null
+++ b/convert.php
@@ -0,0 +1,81 @@
+<?php
+
+if (!isset($argv[1])) {
+    echo 'Usage: php convert.php <psono-json-file.json>' . PHP_EOL;
+    exit;
+}
+
+/**
+ * Recursively get all items into a single array.
+ *
+ * @param array $data - parent data
+ * @param array $items - List of items
+ *
+ * @return array
+ */
+function recursivelyGetItems(array $data, array &$items = []): array
+{
+    if (array_key_exists('items', $data)) {
+        $items = array_merge($items, $data['items']);
+    }
+    
+    // If sub folder.. call again!
+    if (array_key_exists('folders', $data)) {
+        foreach ($data['folders'] as $folder) {
+            if (array_key_exists('items', $folder)) {
+                foreach ($folder['items'] as $subItem) {
+                    $items[] = array_merge(['folder' => $folder['name']], $subItem);
+                }
+            }
+        }
+    }
+    return $items;
+}
+
+// Open source JSON and decode into array
+$rawData = file_get_contents($argv[1]);
+$data = json_decode($rawData, true);
+unset($rawData);
+if (!is_array($data)) {
+    echo 'Error decoding JSON.' . PHP_EOL;
+    exit;
+}
+
+$bitwardenHeaders = [
+    'folder',
+    'favorite',
+    'type',
+    'name',
+    'notes',
+    'fields',
+    'login_uri',
+    'login_username',
+    'login_password',
+    'login_totp'
+];
+
+// Open new file for writing
+$fp = fopen('export.csv', 'w');
+fputcsv($fp, $bitwardenHeaders);
+
+// Get items from nested JSON array
+$items = recursivelyGetItems($data);
+
+foreach ($items as $item) {
+    $mapper = [
+        $item['folder'] ?? '',
+        '',
+        'login',
+        $item['name'],
+        ($item['note_notes'] ?? ($item['website_password_notes'] ?? '')),
+        '',
+        $item['website_password_url'] ?? '',
+        $item['website_password_username'] ?? '',
+        $item['login_password_password'] ?? '',
+        ''
+    ];
+
+    fputcsv($fp, $mapper);
+}
+
+fclose($fp);