YAML Formatter
Validate, beautify, and fix the indentation of YAML in your browser.
Examples
Normalize spacing
Input
name: RunWebTools tags: [a,b]
Output
name: RunWebTools tags: [ a, b ]
Catch a duplicate key
Input
name: test name: again
Output
Map keys must be unique (line 2, column 1)
About this tool
This free online YAML formatter cleans up messy or inconsistent YAML into neatly indented, valid text — a fast YAML beautifier and validator that checks your syntax as it goes and keeps your comments. Paste your YAML, choose an indentation style, and the formatted result appears instantly. Everything runs in your browser with no upload, so your data never leaves your device.
How to use
- Paste your YAML into the input box (or click Sample to try it).
- Pick an indent of 2 or 4 spaces (YAML does not allow tabs).
- Read the beautified YAML in the output box on the right.
- Copy the result with the Copy button.
Why validation matters
YAML is whitespace-sensitive, so a single misaligned line or a stray tab can break a whole config file. The formatter points to the exact line and column of a problem and re-emits valid, consistently indented YAML.
Frequently asked questions
Is this YAML formatter free?
Yes — it's a completely free online YAML formatter, beautifier, and validator with no sign-up and no limits. Format and check as much YAML as you like.
Is my YAML uploaded to a server?
No. This is a no-upload tool — your YAML is parsed and formatted entirely in your browser, so the data never leaves your device. It's safe for config files and secrets.
Does it validate my YAML?
Yes. The tool parses as it formats: if the YAML is invalid it shows the error message with the line and column so you can fix it fast.
Does it keep my comments?
Yes. Unlike a simple parse-and-dump, this formatter preserves your comments while it normalizes indentation and spacing.
Why can't I pick tab indentation?
The YAML specification forbids tab characters for indentation, so this tool offers 2 or 4 spaces only. That keeps the output valid everywhere.
Can it fix inconsistent indentation?
Yes. As long as the YAML is valid, the formatter re-emits it with consistent, correct indentation, which is the most common reason YAML breaks.
Does it work offline and on mobile?
Once the page has loaded it runs locally, so it keeps working on a flaky connection, and the layout is fully responsive on phones and tablets.
Learn more
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