JSON Validator — what it does
Tells you not just that your JSON is broken, but where — the line and character of the offending token, and a plain-English explanation of what the parser expected instead. Built for the moment before lunch break when a config file or webhook payload throws "Unexpected token }" and the console refuses to point at it.
How to use JSON Validator
- Paste the JSON or drop the file.
- If it parses, you get a confirmation plus the top-level structure (object/array, key count).
- If it fails, you get the exact line and column, an arrow pointing at the bad token, and a readable reason — "string not closed", "trailing comma", "keys must be quoted".
- Fix the highlighted spot, re-run, and iterate until the check passes.
- Use Strict mode to also reject duplicate keys and trailing whitespace, which plain parsers silently accept.
Worked example: the trailing comma that eats an afternoon
A deployment fails because a 300-line config has one trailing comma after the last array element. Editors stay silent, the platform's error message names nothing. Paste the config here and the pointer lands on the comma with "expected a property name or ]" — thirty seconds instead of a bisect session.
At a glance
| Input | JSON text or a file from disk |
|---|---|
| Output | Pass/fail, exact error position, plain-English reason |
| Strict options | Duplicate-key detection, trailing-comma rejection |
| Where it runs | Native JSON.parse in your browser — no upload |
| Offline | Works offline after the first visit |
Frequently asked questions
- What is JSON Validator?
- Validate JSON and pinpoint the exact syntax error with a helpful message.
- Is JSON Validator free to use?
- Yes — JSON Validator is free to use, with no sign-up, no install and no account.
- Does JSON Validator upload or store my data?
- No — JSON Validator runs entirely in your browser, so your text, files and results never leave your device.
- Do I need to install anything to use JSON Validator?
- No — it works in any modern browser (Chrome, Edge, Firefox, Safari) with no downloads, accounts or plugins.
- It passed here but my server still rejects it. Why?
- Most server-side parsers are stricter than they advertise. Run it again in Strict mode: duplicate keys and trailing commas are the two things lenient browsers accept and production JSON parsers commonly reject.
- Can it validate JSON Schema as well?
- This tool validates JSON syntax — that a document parses. If you need to check a document against a schema (required fields, types, enums), use the JSON Schema Generator first on a sample and then a schema-aware validator; the two checks answer different questions.
- Does it send my JSON anywhere?
- No. Validation is a local parse — your config with database passwords, customer records and internal hostnames never leaves the tab.