If you want a JSON validator that also formats, try a browser-based JSON formatter and validator: it checks the syntax, points at the error location, and pretty-prints the result in one step. It is free, has no ads, and runs entirely in your browser, so real API payloads never leave your machine.
Free online JSON formatter and validator. Beautify, minify and validate JSON instantly in your browser. No data leaves your device.
Open JSON Formatter & Validator → Free toolFree JSON validator. Check if your JSON is valid, get the exact error location on failure, and see a pretty-printed version when it parses cleanly.
Open JSON Validator →JSONLint is a long-standing free JSON validator and it does that one job well. The case for an alternative is workflow: most of the time you do not just want a verdict, you want the JSON validated, indented and readable in the same step, with the option to minify it back afterwards. A combined formatter-validator saves the round trip between two tools.
This validator parses your JSON entirely in the browser, so payloads containing tokens, emails or internal ids are never transmitted. There are no ads on the page, no account, and no size cap beyond your browser memory, and once the page has loaded it keeps working without a connection.
Yes. Invalid JSON is flagged with the location of the problem so you can fix it quickly.
No. Validation and formatting run entirely in your browser.
Yes. You can pretty-print for reading or minify for compact output from the same tool.