YAML Validator
Validate YAML syntax, find errors with line numbers, and format/beautify YAML files instantly.
Last reviewed by the Radiatus Cloud team
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Find the YAML error and where it is
YAML’s reliance on indentation makes it readable and fragile: a small mistake breaks the whole file, and the parser error is often cryptic. This validator checks YAML syntax, reports errors with their line numbers, and can format the file, so you find and fix the problem quickly instead of hunting for it.
The mistakes YAML invites
The classic YAML errors are all about structure: mixing tabs and spaces, which YAML forbids; inconsistent indentation that changes the nesting; a value like a colon or a leading zero that needs quoting; and a misaligned list item. Because these change meaning rather than obviously breaking, a file can parse into something other than you intended. Validation catches the ones that break the parse and locates them by line.
Line numbers are the point
Knowing that a file is invalid is half the battle; knowing which line is the other half. Reporting the position turns a vague parse failure into a specific fix, and formatting the file afterward makes the structure consistent so the same error is less likely next time. The validation runs in your browser, so your file is not uploaded.
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Frequently Asked Questions
Why does YAML break so easily?
Because it uses indentation for structure and forbids tabs, so a mistyped space, a tab, or a value that needs quoting can break the parse or change the meaning.
Does it tell me where the error is?
Yes. Errors are reported with their line numbers, turning a cryptic parse failure into a specific location you can fix.
Can it format the file too?
Yes. It can beautify the YAML so the indentation is consistent, which makes the structure clear and the same class of error less likely.
Why can a file parse but be wrong?
Because inconsistent indentation can change the nesting into something valid but not what you intended. Validation catches breaks; consistent formatting helps prevent silent misnesting.
Is my file uploaded?
No. The validation runs entirely in your browser.
Privacy & Security
Validated locally in browser.
About This Tool
This tool runs entirely in your browser. No data is sent to any server, ensuring complete privacy. Simply use the interface above to get started — no registration or login required.
Disclaimer: This tool is provided "as is" without warranty of any kind. Results are for educational and utility purposes.