JSON formatter and validator

JSON validator and syntax checker

Check whether your JSON is valid and pinpoint syntax errors instantly. A fast, private JSON linter that runs entirely in your browser.

Input JSON

0 lines | 0 chars
Paste JSON, then validate or transform it.

Output

0 lines | 0 chars

Example

Input JSON
{
  "name": "api",
  "active": true,
  "tags": ["x", "y"]
}
Validation result
Valid JSON. No syntax errors detected.

How to validate JSON

Confirm your JSON parses — and find the problem if it doesn't.

  1. Paste or load your JSON

    Paste the JSON you want to check into the Input panel, upload a .json file, or fetch it from a URL endpoint.

  2. Click Validate

    Click Validate to parse the input. The status bar turns green and confirms the JSON is valid when there are no syntax errors.

  3. Read the error message

    If the JSON is malformed, the status bar turns red with a precise parser message describing what went wrong — a trailing comma, a missing quote, an unexpected token — so you can jump straight to the fix.

  4. Fix and re-check

    Correct the input and click Validate again. Once it passes, use Pretty to clean up the formatting or Convert to transform it to CSV, YAML, or XML.

JSON validation — questions

What the validator checks and how it reports problems.

What does the validator check?

It checks that your input is syntactically valid JSON according to the specification — balanced braces and brackets, correctly quoted keys and strings, valid numbers, and no stray or trailing commas. It uses the same strict parser the browser uses for JSON.parse.

What are the most common JSON syntax errors?

Trailing commas after the last item, single quotes instead of double quotes, unquoted object keys, missing commas between items, and comments — none of which are allowed in standard JSON. The error message points you at the first place parsing failed.

Does it validate against a JSON Schema?

No. This tool validates JSON syntax, not conformance to a JSON Schema. It tells you whether the document is well-formed JSON, not whether it matches a particular set of required fields or types.

Will it accept JSON5 or JSONC (JSON with comments)?

No. Standard JSON does not permit comments, trailing commas, or unquoted keys, so input using those JSON5/JSONC extensions is reported as invalid. Remove them to pass strict validation.

Is my JSON uploaded for validation?

No. Validation happens locally in your browser, so even sensitive payloads stay on your machine and are never transmitted.