YAML Validator
Check YAML syntax with line-by-line errors.
How to use
- 1 Paste your YAML into the input box.
- 2 Read the live status: valid, or a list of errors and warnings.
- 3 Use the line and column in each message to locate the problem.
- 4 Fix and re-check until the YAML reports as valid.
About YAML Validator
The YAML Validator checks whether your YAML is syntactically correct and pinpoints exactly what is wrong when it is not.
Paste a config file, a CI pipeline, a Kubernetes manifest or any other YAML, and it parses the text and reports each error with its line and column so you can jump straight to the problem.
YAML is famously sensitive to indentation, tabs and subtle structural mistakes, and a single misaligned dash or stray tab can break an entire deployment.
This tool surfaces those issues clearly: it tells you when tabs are used for indentation, when a block sequence is mis-indented, when a key is duplicated, and other common pitfalls, separating hard errors from softer warnings.
It also counts the documents in a multi-document stream separated by the “---” marker, which is useful for manifests that bundle several resources together.
Validation happens entirely in your browser using a robust YAML parser, so your data never leaves your machine — nothing is uploaded, logged or stored.
That makes it safe for private configuration containing secrets or internal hostnames, and it keeps working offline once the page has loaded.
Output updates live as you type, so you get immediate feedback while editing rather than waiting for a separate “check” step.
Once your YAML reports as valid, you can be confident it will parse cleanly in your tooling.
FAQ
Does it validate against a schema?
No — it checks YAML syntax and structure, not whether your data matches a particular schema. For schema checks, validate the parsed data separately.
Can it handle multiple documents in one file?
Yes. Documents separated by the “---” marker are each parsed, and the tool reports how many documents it found along with any per-document errors.
Why does it flag tabs?
The YAML specification forbids using tab characters for indentation. The validator points out the exact line so you can replace tabs with spaces.