YAML Validator Online
Validate YAML syntax and preview parsed structure as JSON. Free, no signup, works in your browser.
All validation happens in your browser. No data is sent to any server.
About YAML Validator
This YAML validator checks your YAML for syntax errors in real time. It catches common mistakes like tab indentation (YAML requires spaces), inconsistent indentation levels, and malformed key-value pairs. Valid YAML is automatically parsed and displayed as formatted JSON so you can verify the structure matches your expectations. Useful for validating configuration files for Docker Compose, Kubernetes, GitHub Actions, Ansible, and other tools that rely on YAML.
Frequently Asked Questions
Why is my YAML invalid because of tabs?
YAML requires spaces for indentation — tab characters are not allowed. Replace any tab characters with 2 or 4 spaces. Most editors have a setting to convert tabs to spaces automatically.
What YAML features does this validator support?
The validator supports objects (mappings), arrays (sequences), nested structures, inline arrays and objects, strings (quoted and unquoted), numbers, booleans, null values, and comments. It covers the YAML subset used by most configuration files.
Can I convert YAML to JSON with this tool?
Yes. When your YAML is valid, the tool automatically displays the parsed structure as formatted JSON. Click 'Copy JSON' to copy it to your clipboard. For full bidirectional conversion, try our JSON ↔ YAML Converter.