Validate YAML Online
Validate YAML online and get a clear pass or fail result so syntax errors in config files, deployment manifests, CI pipelines, and Kubernetes resources are caught before use. Paste your YAML and the validator checks indentation, key structure, and syntax rules, then returns a readable result.
How to use YAML Validator
Paste content into the yaml input panel.
Run the validator to check for success messages, syntax issues, or invalid structure.
Review the result, then copy or download it if you need to share the outcome.
Why this helps in real workflows
A Kubernetes manifest or Helm values file is failing to apply and you want to confirm whether the YAML syntax is the cause before investigating further.
A GitHub Actions or GitLab CI pipeline definition has an error and you want to isolate whether it is a YAML syntax problem.
A config file edited by hand or generated by a script needs a syntax check before it is committed or deployed.
YAML copied from documentation or a template has inconsistent indentation and you want to confirm it is valid before using it.
Common problems and fixes
The validator reports an error but the YAML looks correct.
YAML is sensitive to indentation — mixing tabs and spaces is always invalid. The error message includes the line number. Check that line for tab characters, inconsistent spacing, or a colon inside an unquoted string value that YAML is interpreting as a key separator.
The YAML file is valid but still fails in Kubernetes or my CI tool.
YAML validation only checks syntax. Kubernetes and CI tools also enforce their own schema rules — required fields, valid values, and correct resource structures. A YAML file can be syntactically valid but still be rejected by the target tool for schema reasons.
Multiline strings are causing a validation error.
Multiline strings in YAML require a block scalar indicator — | for literal blocks or > for folded blocks — after the key. Without it, YAML will try to parse the next line as a new key and fail. Add the indicator and ensure the content is consistently indented.
Related tools
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Frequently asked questions
How do I validate YAML?
Paste your YAML into the input box, run the validator, and review the validation result in the output panel.
Will the YAML validator show syntax errors?
Yes. Invalid YAML returns an error message with the line number and a description of the problem.
Is this YAML validator free?
Yes. It is free to use in your browser.
Can I use tabs for indentation in YAML?
No. YAML requires spaces for indentation — tabs are not allowed and will always cause a parse error. Configure your editor to insert spaces instead of tabs when working with YAML files.
Does valid YAML mean my Kubernetes manifest will work?
Not necessarily. Valid YAML means the syntax is correct. Kubernetes also checks the manifest against its own schema — required fields, correct resource kinds, and valid values. Both need to be right for the manifest to apply successfully.
Can I format the YAML after validating it?
Yes. Once you confirm the YAML is valid, paste it into the YAML Formatter to normalise indentation and spacing.