YAML Validator
Validate YAML live — a precise line:column code-frame on the error and a multi-document count for valid input.
About this ToolHow it works, benefits & use casesTap to collapse
The YAML Validator checks whether your YAML parses cleanly and, when it does not, shows you exactly where it breaks. Paste YAML and it validates live, displaying a green "Valid YAML" confirmation or a red error with the message, the line and column, and a code-frame snippet with a caret pointing at the problem. It is multi-document aware: files that use the --- separator to hold several documents are parsed in full, and the success banner reports how many documents were found. Because indentation and unterminated strings are the most common YAML pitfalls, the error reporting focuses on giving you an accurate line and column to fix. Two sample buttons let you load a valid configuration or a deliberately broken one — with bad indentation and an unterminated string — to see how the validator responds. It runs entirely in your browser, uploads nothing, and is free.
How to Use
- 1Paste your YAML into the input panel, or use "Load example" for a valid file or "Broken sample" to see an error.
- 2Validation runs live as you type; click "Validate YAML" to confirm.
- 3On success, read the "Valid YAML" banner with the document count.
- 4On failure, use the code-frame error with its line:column and caret to locate the indentation or syntax issue.
- 5Fix the highlighted problem and watch the result update immediately.
Key Benefits
- Live validation with a clear valid/invalid result
- Precise line:column code-frame and caret on parse errors
- Multi-document aware — counts documents separated by ---
- Surfaces the common culprits: bad indentation and unterminated strings
- Built-in valid and broken samples to demonstrate both outcomes
- No formatting or schema setup required — just paste and check
- Runs entirely in the browser — YAML is never uploaded
Common Use Cases
- Catching an indentation mistake in a CI pipeline or Kubernetes manifest
- Validating a docker-compose or GitHub Actions file before committing
- Checking a multi-document YAML stream parses into the expected number of documents
- Locating an unterminated string or bad mapping in a config file
- Confirming hand-edited YAML is well-formed before deploying it
0 characters · live · multi-document aware
Paste YAML above to validate it live.
Was this tool helpful?
Share Your Experience
Help others discover this tool!
Related tools
- Render Config GeneratorBuild a render.yaml blueprint — services (web/worker/cron/static), databases, typed env vars, fromDatabase links — with live YAML and an audit
- Docker Compose GeneratorGenerate docker-compose.yml files
- GitHub Actions GeneratorVisual workflow builder — triggers, jobs, a build matrix, job dependencies, and steps from a real action catalogue, with live YAML and a linter
- Code Block FormatterFormat code blocks for Markdown
- GraphQL Schema ValidatorValidate GraphQL schema definitions
- Twitter Card ValidatorValidate Twitter Card meta tags
Yes. YAML files can contain several documents separated by --- markers, and the validator parses all of them. On success the banner reports the document count, so you can confirm a multi-document stream contains the number of documents you expect.
When parsing fails, the validator reports the error message with a line and column and renders a code-frame snippet: the relevant line with a caret (^) beneath the column. YAML errors are frequently caused by indentation, so an accurate position helps you find the misaligned key or list item quickly.