Free online YAML validator & formatter - Real-time syntax checking, auto-beautification, pure client-side
YAML (YAML Ain't Markup Language) is more human-readable than JSON, supports comments, multi-line strings, anchors and aliases. JSON is a stricter data format with simpler syntax but lower readability. YAML is a superset of JSON.
Common errors include: inconsistent indentation (YAML requires consistent indentation at the same level), missing space after colon, unescaped special characters, mixing tabs and spaces (YAML doesn't allow tabs), and multi-line string format errors.
Completely secure. All YAML parsing and validation happens locally in your browser. Your data is never uploaded to any server. Your configuration content always stays local.
No. YAML Lint uses client-side processing — everything runs in your browser. Your data never leaves your device, and the tool works even without an internet connection.
Yes, YAML Lint is completely free to use. No registration or login required — all features are available immediately.
YAML Lint has no usage limits — it's free and unlimited. Since processing is done client-side, speed depends on your device. For very large files, we recommend processing in batches for the best experience.
Yes. YAML Lint is fully responsive and works on phones, tablets, and desktops. The interface adapts automatically to your screen size.
No. YAML Lint is a web-based tool — just open it in your browser and start using it. No downloads, plugins, or extensions required.