Free JSON Validator — Check & Format JSON Online

One misplaced comma and your whole API call fails. Paste your JSON below and get an instant verdict — valid or broken, the exact error position, a pretty-printed version, and useful stats. Everything runs locally in your browser.

How it works

1. Paste your JSON — from an API response, config file, or anywhere else.
2. Hit Validate JSON — the parser checks every character locally and reports the exact error position (line and column) if something is wrong.
3. Copy the formatted version — valid JSON is pretty-printed with 2-space indentation, ready to paste back.

Everyday uses

• Developers — debug API responses and config files before they break your app.
• Students — learn JSON syntax with instant, precise error feedback.
• Data analysts — sanity-check exported datasets before importing them.
• No-code builders — validate webhook payloads for tools like Zapier or Make.
• Writers & editors — safely format JSON-LD schema snippets for web pages.

Frequently asked questions

What are the most common JSON errors? Trailing commas, single quotes instead of double quotes, unquoted keys, and comments — none of which JSON allows. The validator points at the exact character where parsing stopped.

Is there a size limit? No hard limit — but very large documents (tens of megabytes) may take a moment since everything is parsed in your browser tab.

Does my JSON get uploaded anywhere? No. Validation and formatting run entirely in your browser with the built-in JSON parser — nothing is sent to any server.

What’s the difference between the stats shown? Top-level keys/items counts what’s at the root, nesting depth measures how many levels deep the structure goes, and the byte size is the UTF-8 encoded size.