Is my JSON sent to a server?

No. Validation runs entirely in your browser.

What counts as valid JSON?

Valid JSON must use double quotes for keys and strings, and follow standard JSON syntax (no trailing commas, etc.).

Runs in browser

Validate JSON syntax and see exact error messages instantly.

Validate JSON syntax in your browser. Paste any string to check if it is valid JSON. See the exact error and position when invalid.

JSON input

Files never leave your browser.

Drag and drop a file here, or tap to select

Valid JSON.

🔒 Runs in your browser · No uploads · Your data never leaves your device

Paste your JSON
Enter or paste the text you want to validate in the text area.
Check result
The tool reports whether the input is valid JSON. If invalid, you'll see the error message.
Copy if valid
When valid, use the Copy button to copy the JSON.

Fixing malformed API responses — Paste a JSON string that's causing a parse error to identify exactly which character or line is invalid.
Validating config files — Check JSON configuration files like tsconfig.json or package.json for syntax errors before committing.
Debugging webhook payloads — Validate JSON payloads received from third-party webhooks to ensure they conform to expected structure.

Is my JSON sent to a server?: No. Validation runs entirely in your browser.
What counts as valid JSON?: Valid JSON must use double quotes for keys and strings, and follow standard JSON syntax (no trailing commas, etc.).

JSON syntax: The rules governing valid JSON: keys must be double-quoted strings, values must be valid JSON types, and no trailing commas are allowed.
Parse error: An error thrown when a JSON string violates syntax rules and cannot be converted to a JavaScript object.
JSON linting: The process of checking JSON for syntax errors — analogous to code linting but for data format correctness.

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