JSON validator
Paste JSON to find out whether it is valid — and if not, exactly where and why.
Runs in your browser. Nothing you enter is sent to our server.
About this tool
The validator follows the JSON standard (RFC 8259) strictly. It catches extra and missing commas, unclosed brackets and quotes, single quotes, comments, NaN, undefined and invalid escape sequences.
Instead of a cryptic “Unexpected token” you get the line and column, the offending line with a pointer and a plain explanation. Valid JSON gets a short summary of its structure.
How to use
- Paste JSON into the field.
- Click “Validate” — or just wait, validation runs as you type.
- Fix the error at the reported position and check again.
Examples
{'id': 1}Line 1, column 2: expected a property name in double quotes
{"items": [1, 2, 3]}Valid JSON: 1 object, 1 array, 1 key
Frequently asked questions
How is the validator different from the formatter?
The validator only checks and explains errors in detail. The formatter also reformats or minifies valid JSON.
Are comments (JSONC, JSON5) supported?
No. It validates strict JSON, which is what most APIs and JSON.parse expect.
Why is the error reported after my actual mistake?
The parser reports where the text stopped being valid JSON. A missing quote or bracket often starts the problem earlier than that position.