Online Tool Store
YAML Validator
Validate YAML syntax with a live JSON preview and precise line/column error locations. Runs entirely in your browser.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
Nothing is uploaded — parsing runs entirely in your browser.
How it works
- Paste or type YAML on the left.
- See the parsed result as JSON on the right, updated as you type.
- If there's a syntax error, the exact line and column are shown so you can fix it fast.
FAQ
Why does it flag indentation that looks fine to me?
YAML is whitespace-sensitive, and mixing tabs and spaces (even invisibly) or being off by one space at a nesting level are the most common causes of a parse error — the error message includes the exact line and column so you can spot it.
What parser is this using?
js-yaml, a widely used, actively maintained YAML 1.2 parser (the same one many JavaScript tools and CI systems rely on) — so a file that validates here should parse the same way in a real YAML-consuming tool.
Does the JSON preview mean my YAML converts perfectly to JSON?
For most YAML, yes — JSON is close to a subset of YAML's data model. A few advanced YAML features (anchors/aliases referencing shared structures, multiple documents in one file) don't have a clean 1:1 JSON equivalent, but the preview still shows the resolved data.
Is my YAML uploaded anywhere?
No — parsing runs entirely in your browser using the js-yaml library. Nothing you type is sent anywhere.
How we compare
| Feature | Online Tool Store | YAML Lint | IDE YAML extension |
|---|---|---|---|
| Live JSON preview alongside the error check | ✓ | Validation only, no JSON view | Varies by extension |
| No install | ✓ | ✓ | Requires an IDE + extension |
| No ads | ✓ | Ad-supported | ✓ |
Handy for a quick sanity check on a config snippet without switching to your editor at all.