Validate JSON Online — Free
Validate JSON online — free, no upload, no signup, runs entirely in your browser. Paste any JSON string and instantly see whether it's syntactically valid plus the exact line and column of any error. The validator handles trailing commas, mismatched brackets, unquoted keys, and invalid escapes with clear, actionable error messages. Useful for debugging API responses, config files, package.json edits, and webhook payloads. Because validation runs locally, even production secrets and internal API responses stay safe on your device.
How to validate json online
- Paste your input (JSON, JWT, CSV, or other text) into the tool above.
- Choose the format/option you need — everything is computed in your browser.
- Copy the result with one click, or download it as a file.
Common use cases
- Debugging API responses and inspecting JWT payloads
- Pretty-printing minified JSON copied from network tabs or logs
- Converting between data formats (CSV ↔ JSON, JSON ↔ YAML)
- Validating syntax before pasting into config files
- Sharing readable snippets with teammates in pull requests
Frequently asked questions
What does JSON validation check?
Syntax: balanced brackets, quoted keys, valid escapes, allowed value types, and proper comma placement.
Does it validate against a schema?
No — this checks pure JSON syntax. For schema validation use a JSON Schema tool.
Are my JSON payloads uploaded?
No — validation runs entirely in your browser. Production API responses are safe to paste here.
Will it find the exact error line?
Yes — error messages include the line and column where the parser failed.