JSON Validator

Validate your JSON data and get detailed error messages.

ToolsSoup's JSON Validator is a free online tool that instantly checks whether your JSON is valid and, when it is not, pinpoints the exact line and column of the first error with a clear message and a caret pointing at the problem. Everything runs in your browser — no uploads, no sign-up, and your data never leaves your device.

What is a JSON validator?

A JSON validator parses your text against the strict JSON standard and tells you whether it is well-formed. If the JSON is valid, you get a confirmation along with a quick summary of the root value. If it is invalid, the validator reports a precise location — line and column — plus the offending character, so you can fix syntax errors fast instead of squinting at a wall of text. Developers use it to debug API responses, configuration files, and data copied from logs.

How to validate JSON online

Validating JSON with ToolsSoup takes just a few seconds:

  1. Paste or type your JSON into the input box.
  2. Click Validate to check it against the JSON specification.
  3. Read the result: a green confirmation if it is valid, or a red message with the exact line, column, and a caret marking the first error.

Common JSON syntax errors

Most 'Invalid JSON' messages come from a small set of mistakes: trailing commas after the last item, single quotes instead of double quotes, unquoted object keys, missing or mismatched brackets and braces, and stray comments (JSON does not allow them). The validator highlights where the parser first gives up so you can correct it quickly.

Why use this JSON validator?

  • 100% free with no ads, sign-up, or usage limits.
  • Runs entirely in your browser — your data is never uploaded to a server.
  • Pinpoints the exact line and column of the first syntax error.
  • Shows the offending line with a caret so the problem is obvious.
  • Confirms valid JSON and summarizes the root value at a glance.

Frequently asked questions

Is this JSON validator free?

Yes. Every tool on ToolsSoup is completely free to use, with no account, sign-up, or hidden limits.

Is my JSON data safe?

Absolutely. All validation happens locally in your browser using JavaScript, so your JSON is never sent to or stored on any server.

What is the difference between validating and formatting JSON?

Validating checks whether your JSON follows the standard and tells you exactly where any error is, while formatting (beautifying) rewrites valid JSON with clean indentation. Use the JSON Validator to find and fix errors, then the JSON Formatter to tidy up the result.

Why is my JSON invalid?

The validator follows the strict JSON standard. The most common causes are trailing commas, single quotes instead of double quotes, unquoted keys, missing brackets, and comments. Check the line and column shown in the error and fix the highlighted character.

Can I validate large JSON files?

Yes. Because everything runs on your own device, you can validate large JSON documents quickly with no upload limits, though very large files will depend on your browser's available memory.