YAML Validator
Validate YAML and get the exact line and cause of every error.
Input
Output
Ready
Drop a file to load it
About this tool
Check that a YAML document is well-formed, with errors reported by line and column and explained rather than just named.
When you would use it
- Catching a malformed YAML document before it reaches production
- Finding the exact position of a syntax error
- Checking a file a tool rejected
Worked example
id: 4815 name: Ada Lovelace active: true score: 91.5 roles: - admin - editor address: city: London postcode: NW1
Valid · 1 documents · 8 keys · 2 items · 3 depth
Things worth knowing
- Indentation mistakes are the most common YAML error and are reported with the line where the indent changes unexpectedly.
- Tabs are rejected the way a real YAML parser rejects them, since YAML forbids tabs for indentation.
Questions
Frequently asked
What does "well-formed" mean for YAML?
The document parses without ambiguity: consistent indentation, no tabs, and every alias resolving to a defined anchor.
Is my data uploaded anywhere?
No. Every tool on JSONWorks runs entirely in your browser using JavaScript. Your input is never sent to a server, never logged and never stored. The simplest proof is to disconnect from the internet — the tools keep working. The site does load Google Fonts and a Google Analytics page-view tag, so you will see those two requests in your network tab, but neither receives anything you type or paste.
Does it work offline?
Yes. JSONWorks is installable as a progressive web app and caches itself on first visit, so every tool keeps working without a connection.
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