JSON Validator
Validate JSON in real time with exact error lines and plain-English explanations. 100% private.
JSON to Validate
Validation runs on every keystroke.
Result
By Vizo ToolLast updated August 20263 min read
JSON Validator — Check Your JSON in Real Time
The JSON Validator checks your JSON as you type, with instant green/red feedback, the exact line and column of any problem, and a plain-English explanation of what went wrong. No more hunting through braces by eye.
Valid JSON can be pretty-printed with one click, and everything runs locally in your browser — so test API responses, config files, and webhook payloads in complete privacy.
- Real-time validation
- Error line numbers
- Plain-English errors
- Pretty print
Why Use JSON Validator?
Validate as You Type
Real-time feedback shows instantly whether your JSON is valid.
Pinpoint Errors
Get the exact line and column plus a human-readable reason for every problem.
One-Click Pretty Print
Turn valid JSON into clean, indented output in a single click.
Private by Default
Nothing is uploaded — validation runs entirely on your device.
Features
Real-Time Checking
Every keystroke re-validates instantly with a clear pass/fail indicator.
Error Line & Column
Precise position reporting with the offending snippet highlighted.
Plain-English Explanations
Understandable messages like 'Missing closing brace' instead of cryptic codes.
Pretty Print
Format valid JSON into readable, 2-space indented output.
Copy Results
Copy the formatted JSON or the error report to the clipboard.
How to Validate JSON
Check and fix your JSON in three simple steps.
Paste your JSON
Paste or type JSON into the editor — validation starts immediately.
Read the feedback
A green badge confirms it's valid; a red badge shows the line, column, and explanation.
Fix or format
Correct the reported issue, or pretty-print valid JSON for a cleaner copy.
Frequently Asked Questions
Got questions? We've got answers.
What is a JSON validator?▼
A JSON validator checks whether a string is syntactically valid JSON and reports exactly where problems occur, with human-readable explanations.
Is validation instant?▼
Yes, the tool validates on every keystroke in real time — no submit button needed.
Is the JSON validator free?▼
Yes, completely free with no sign-ups or limits.
Are my JSON payloads uploaded?▼
No. Validation runs entirely in your browser; your data never leaves your device.
What does the line number mean?▼
It's the 1-based line in your input where the parser found a problem, so you can jump straight to the error.
Why does it say 'Unexpected token'?▼
That means a character appeared where the JSON grammar didn't expect it — commonly a stray comma, quote, or brace.
Can it validate a JSON file?▼
Yes — upload a .json file and it's validated immediately. You can also download the pretty-printed result.
Does pretty print change my data?▼
No, it only adds whitespace. The parsed data is identical; pretty print just makes it readable.
Can trailing commas be validated?▼
Trailing commas are invalid in standard JSON, so they are reported as errors — which is correct behavior.
Does it work on mobile?▼
Yes, the tool is fully responsive and works on any device.
Can I copy the error report?▼
Yes, the error message and position can be copied for sharing or debugging.
What's the difference between this and the JSON formatter?▼
The validator focuses on checking correctness with real-time feedback, while the formatter adds beautify, minify, and a tree view.
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