JSON Validator
Validate and lint JSON with detailed error messages
JSON Validator is a free online tool from BrowserUtils that validate and lint json with detailed error messages. It runs entirely in your browser — your data never leaves your device. No account required.
How to use JSON Validator
- 1 Paste or type your input into the editor above.
- 2 The tool processes your data instantly — right in your browser, with nothing sent to a server.
- 3 Copy the result with one click or continue editing your input.
About JSON Validator
Free online JSON validator and linter. Check if your JSON is valid and get precise error locations with helpful messages. This tool runs entirely in your browser — your data is never sent to a server. Just paste your input, get instant results, and copy with one click. No sign-up or installation required.
JSON Validator specs
- Runtime
- 100% client-side (browser)
- Built on
- Native JavaScript JSON.parse / JSON.stringify (RFC 8259 compliant)
- Cost
- Free — no account, no rate limits, no usage caps
- Browser support
- Chrome 90+, Firefox 88+, Safari 14+, Edge 90+
- Part of
- 299 developer tools on BrowserUtils (100% client-side)
Questions
How do I validate JSON?
Paste your JSON into the input field. The validator will instantly check the syntax and show any errors with line numbers and descriptions.
What are the most common JSON syntax errors?
The most common errors are trailing commas after the last item, single quotes instead of double quotes, unquoted keys, and missing closing brackets or braces.
Can I validate JSON from an API response?
Yes, paste any JSON string from an API response, log file, or config file and the validator will check it. It works with any valid or invalid JSON text.
Is my data safe when validating JSON online?
Yes, validation runs entirely in your browser. Your JSON data never leaves your device and is not stored or transmitted anywhere.
Can the JSON validator fix errors automatically?
The validator identifies and locates errors but does not auto-fix them. It shows the exact line and character position so you can correct the issue yourself.
How do I validate a large JSON file?
Paste the JSON directly into the input. The validator processes the entire document in your browser, so there is no file size limit imposed by a server, though very large files may be slow on older devices.
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