JSON Validator
Check whether JSON is valid, and get the exact position and likely cause when it is not.
How to use this tool
- Paste or type your text into the box above.
- The result updates as you change the input — there is nothing to submit and nothing to wait for.
- Read the figures in the result panel, or copy the converted text.
- Use Copy or Download if you need the output elsewhere. Nothing was uploaded at any point.
Validation uses your browser’s own JSON parser, so the answer matches exactly what your code will do with the same input.
JSON Validator — the specification
| Result | Valid or invalid, with position on failure |
|---|---|
| Reports | Type, key count, nesting depth, size |
| Engine | The browser’s native JSON parser |
| Privacy | Nothing leaves your device |
How it works
This tool runs entirely in your browser. There is no server involved, which means nothing you type or upload is transmitted, stored, or logged — and there are no usage limits, because there is nothing for us to ration.
You can confirm it yourself: open your browser's developer tools, select the Network tab, and use the tool. No request is made.
A worked example
Run against this page’s own code, with the real input and the real output reproduced below.
What went in
{"exam":"SSC CGL","photo":{"min":20480,"max":51200,},"signature":null}
What came back
Invalid JSON at line 1, column 52. Expected double-quoted property name in JSON at position 51 (line 1 column 52)
Near: …oto":{"min":20480,"max":51200,},"signature":null}…
Common causes: a trailing
That input was deliberately broken — note the trailing comma before the closing brace. A validator that only says “invalid” leaves you hunting; this one gives the line, the column and the likely cause, which is the whole job.
Who needs JSON Validator
Debugging an API payload, checking a config file before deployment, or confirming that generated JSON is well-formed.
JSON Validator — frequently asked questions
Does this check against a schema?
No. It checks syntax only — whether the text is parseable JSON. Validating structure against a JSON Schema is a different job and needs a schema to validate against.
What is nesting depth?
How many levels of objects and arrays are inside one another. Deeply nested JSON is harder to work with and some parsers impose limits.
Are comments allowed in JSON?
No. The JSON specification has no comments. Formats such as JSONC and JSON5 add them, but standard parsers reject them.
Does this work offline?
Yes. Once the page has loaded you can disconnect from the internet and it keeps working, because all the processing happens in your browser. That is also the simplest way to confirm nothing is being sent anywhere.
Is there a limit on how much I can paste in?
Nothing we impose. The practical limit is your device’s memory, since the work happens locally. Very large inputs get slower rather than being refused.
Can I use this on a phone?
Yes. The layout adapts to a small screen and everything works the same way.
Related tools
From other categories
Background reading: Text and Developer Tools That Never Upload Your Data
Your file never leaves your device. Open your browser's Network tab while you use this page and you will see no upload — how that works.
Disclaimer. Published requirements change without notice. Confirm against the official source before you submit. Full disclaimer.