Free Online JSON Validator
Broken JSON rarely fails politely. One trailing comma after the last array item, a stray smart quote pasted from a blog post, an unescaped newline inside a string — and your config file, API response or infrastructure template refuses to parse, often pointing at a line far from where the real mistake lives. This validator catches those errors the moment you paste, pinpoints the exact character position, and tells you in plain language what went wrong.
Validation runs live as you type: valid JSON shows a clean parse with formatted structure available at a glance, while invalid input gets flagged inline with the error location highlighted — no "Validate" button ceremony, no round trips. Beyond syntax checking, seeing your data pretty-printed makes logical problems obvious too: duplicated keys, wrong nesting levels and missing fields jump out once the structure is readable.
Because parsing happens with your browser's own JSON engine, behavior matches what your application will see — no server-side interpretation differences to chase. Config files containing internal hostnames, API responses with customer data, secrets under review: everything stays on your machine, always.
How to Use This Tool
- Paste your JSON — from a file, API response, log line or editor.
- Check the verdict instantly — valid input confirms; errors show position and reason.
- Fix and iterate — correct the flagged spot and watch validation clear in real time.
Benefits
- Live validation — instant feedback on every edit.
- Precise error positions — line and column, not vague complaints.
- Pretty-printed view — structural mistakes become visible.
- Engine parity — uses your browser's native JSON parser.
- Free and local — unlimited checks, zero uploads.