What YAML features are supported?

String, number, boolean, and null scalars; nested objects (indentation-based); sequences (- item lists); quoted strings (single and double); inline booleans (true/false/yes/no/on/off). Multi-line strings, anchors, and aliases are not supported.

Is this a full YAML parser?

No. This is a lightweight hand-rolled parser that covers the majority of real-world YAML use cases without relying on external libraries. For production parsing, use a full YAML library in your server-side code.

What does the JSON output look like?

The JSON output is formatted with 2-space indentation, exactly like JSON.stringify(obj, null, 2). Arrays and objects are fully expanded.

Why does my YAML show an error?

Common causes: inconsistent indentation (must use spaces, not tabs), missing space after colon in key-value pairs, or YAML features not supported by this lightweight parser.

developer Free No signup

YAML Validator & Formatter

Validate YAML syntax and convert it to formatted JSON — entirely in your browser.

Loading tool…

About this tool

Paste YAML and instantly check whether it is valid. The built-in parser handles scalars (strings, numbers, booleans, null), nested objects via indentation, and sequences with the - prefix. Switch to JSON view to see your YAML converted to formatted JSON. Error messages show the line number for quick debugging.

How to use

1 Paste your YAML into the input textarea.
2 Click 'Validate' to check for syntax errors.
3 Click 'Convert to JSON' to see the JSON representation.
4 Fix any errors shown — the error message includes the line number.

Frequently Asked Questions

Related tools

JSON Formatter & Validator

Format, validate, and minify JSON — with syntax error pinpointing.

CSV ↔ JSON Converter

Convert CSV data to JSON and JSON arrays back to CSV — with delimiter options and live preview.

HTML / CSS / JS Minifier

Minify HTML, CSS, and JavaScript to reduce file size — runs entirely in your browser.