What is the difference between JSON validation and JSON formatting?

Validation checks whether the JSON is syntactically correct according to the JSON specification. Formatting only changes the visual presentation (indentation, whitespace). You can format valid JSON, but formatting will fail if the JSON is invalid.

What makes JSON invalid?

JSON is invalid if it contains: trailing commas, single-quoted strings, unquoted keys, comments, undefined or NaN values, mismatched brackets, missing colons, or control characters that are not properly escaped.

Should I validate JSON before sending an API request?

Yes. Validating your request body before sending it prevents server errors and speeds up debugging. A quick validation check here takes seconds and can save significant time troubleshooting a failed API call.

Does this validator check JSON Schema compliance?

This tool validates JSON syntax (RFC 8259). It does not validate against a custom JSON Schema (like draft-07 or 2020-12). For schema compliance, you need a dedicated schema validator tool.

Are null and boolean values valid in JSON?

Yes. JSON supports four primitive value types: strings (double-quoted), numbers, booleans (true/false in lowercase), and null. Note that undefined, NaN, and Infinity are not valid JSON values — they are JavaScript-specific.

JSON Validator Online

Check if your JSON is syntactically valid with instant, precise error reporting — no signup, no server upload, works on any device.

Input JSON

Output

Options

Indent: Sort keys A–Z

Why Validate JSON Online?

A JSON validator online is an essential tool for developers, API integrators, and anyone working with data files. JSON has a strict syntax — a single misplaced comma or an unquoted key will cause your entire application to fail at runtime. Validating JSON before deploying it catches those issues in seconds rather than hours of debugging.

Common scenarios where a JSON syntax checker is invaluable: checking an API request payload before sending it, verifying a config file before deploying, reviewing data exports from databases, and debugging webhook payloads that fail silently.

How to Validate JSON Online

Paste your JSON into the Input JSON field above
Click the green Validate button
A green status bar means your JSON is valid — no errors found
A red status bar shows the exact error message with position info
Click Format to pretty-print valid JSON for easier reading

What JSON Validation Checks

This online JSON validator performs syntax validation according to RFC 8259 — the official JSON standard. It checks that:

All strings use double quotes (not single quotes)
All object keys are quoted strings
No trailing commas exist after the last item in objects or arrays
All brackets and braces are properly matched and closed
Values are one of the valid JSON types: string, number, boolean, null, object, or array
Special characters inside strings are properly escaped with backslashes

If any of these rules are violated, you get an instant error message pointing you to the problem location. Pair this with our JSON error fixer guide to resolve issues quickly.

Tips for Clean JSON Every Time

Always validate JSON config files before committing them to version control
When generating JSON programmatically, use JSON.stringify() — it produces valid JSON automatically
Use JSON pretty print after validation to make the structure easy to inspect
Validate early — catching a JSON error before an API call saves round-trips and debugging time

Related JSON Tools

🛠️ JSON Formatter ✨ JSON Pretty Print 🔧 Fix JSON Error 📂 Format Large JSON 🔐 Base64 Encoder 🔗 URL Encoder

Frequently Asked Questions

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