JSON Validator
Check whether your JSON parses and see the exact error location.
- Reading time:
- 2 min
- Last updated:
- Price:
- Free, no signup
Type or paste text to see the result.
What the JSON Validator does
Paste JSON and find out instantly whether it's valid — and if not, exactly where it broke. Instead of a vague 'unexpected token' from your app, you get the line and position of the trailing comma, missing quote or unclosed brace that caused it.
Valid JSON is confirmed with a formatted, indented view, so you can inspect the structure you actually have.
Why the JSON Validator is useful
JSON is unforgiving: one trailing comma or single-quoted string and the whole payload fails. When an API rejects your request or a config file won't load, the error message rarely tells you where to look.
Hand-edited JSON — config files, test fixtures, API payloads — is where these errors live, and they're invisible to the eye in a large file.
Also known as: json validator, json checker, free json validator, online json validator, json validator online free, json validator tool, best json validator tool.
How to use the JSON Validator
- 1
Paste your JSON
Drop in the payload, config or response that's failing.
- 2
Read the verdict
Valid JSON is formatted; invalid JSON gets an error with line and position.
- 3
Fix and re-check
Correct the flagged spot and validate again until it passes.
Key features
- Instant validation with exact error location
- Formatted, indented view of valid JSON
- Handles large payloads
- Private — data never leaves your browser
Benefits
- Find syntax errors in seconds, not by scanning
- Verify API payloads before sending
- Check config files before deploying
Real-life use cases
Debugging an API request
A developer pastes the request body that keeps returning 400 and finds a trailing comma after the last property.
Checking a config file
A sysadmin validates an edited settings.json before restarting the service, catching a missing quote.
Verifying test data
A QA engineer confirms a fixture file is valid before the test suite runs against it.
Tips for the best results
- The most common errors: trailing commas, single quotes instead of double, and unquoted keys.
- JSON doesn't allow comments — if your config has them, that's the failure.
- Fix the first reported error and re-validate; later errors are often just fallout from the first.
Conclusion
Paste it, find the break, fix it, ship it.
Frequently asked questions
What makes JSON invalid?
- Trailing commas, single quotes, unquoted keys, comments, and mismatched brackets are the usual causes.
Does it show where the error is?
- Yes — the error message includes the line and character position of the problem.
Can it format valid JSON too?
- Yes, valid input is shown pretty-printed with indentation.
How big can the payload be?
- Only your machine's memory matters — validation is local and we set no cap.
Is my data uploaded?
- No. Everything stays in your browser tab, which matters for payloads containing sensitive data.
Does it check the data types, not just syntax?
- It validates syntax. Schema validation — checking that fields have the right types — is a separate step.
Related tools you may need
- JSON Formatter — Validate and pretty-print JSON with 2-space indentation.
- CSV to JSON Converter — Turn CSV rows into a JSON array of objects.
- CSV Validator — Check that every row has the same number of columns.
- JSON Diff Checker — Compare two JSON documents and list every difference.
- JSON Path Extractor — Pull a value out of JSON using a dot-notation path.
- JSON to CSV Converter — Turn a JSON array of objects into CSV rows.
- XML Formatter — Beautify XML with clean two-space indentation.
- JWT Decoder — Decode a JWT's header and payload without verifying it.
Keep exploring
Browse the full tools directory, filter by category, or read guides on the Text Tools Hub blog.