JSON Validator — The JSON validator tells you in plain language whether a document is valid JSON, and when it is not, exactly where the first problem is. Instead of a cryptic stack trace you get a friendly message with line and column numbers.
Validation runs locally in your browser. Your JSON is never transmitted or stored.
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What is json validator?
The JSON validator tells you in plain language whether a document is valid JSON, and when it is not, exactly where the first problem is. Instead of a cryptic stack trace you get a friendly message with line and column numbers.
It uses the same parser your browser and most runtimes rely on, so a document that passes here will parse with JSON.parse in JavaScript and equivalent parsers elsewhere.
How to use it
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Paste your JSON
The check runs automatically as you type or paste.
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Read the verdict
A green banner means valid; a red banner shows the error location.
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Fix and re-check
Correct the reported line and column, and the verdict updates instantly.
Examples
Trailing comma
A trailing comma after the last property is the most common JSON mistake.
{
"a": 1,
} Result: Invalid — expected a property name after the comma (line 3).
Frequently asked questions
Comparison: this tool vs the alternatives
Uttir JSON Validator vs JSONLint
| Feature | Uttir | JSONLint |
|---|---|---|
| No upload to a server | ✓ | ✗ |
| No signup | ✓ | ✓ |
| Reports line + column on error | ✓ | ✓ |
| Handles large documents (multi-MB) | ✓ | ✗ |
| No daily limit | ✓ | ✗ |
| No ads | ✓ | ✗ |
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Last reviewed: 2026-09-18