JSON Validator
Validate JSON syntax
What Is This Tool?
The JSON Validator checks whether a block of text is syntactically valid JSON. If it isn't, it tells you exactly where the parser failed — the line and column — so you can fix the problem instead of guessing. All checking happens locally in your browser.
How to Use
Paste your JSON into the input box.
Click Validate.
Read the green "Valid" or red "Invalid" badge, plus error detail if invalid.
Copy the result summary if you need to share it.
Features
- Clear Valid / Invalid status badge
- Line and column error reporting
- Copy the validation result as text
- No file size restrictions beyond your browser's memory
- 100% client-side — nothing leaves your browser
Examples
Valid: {"id": 1, "active": true}
Invalid: {"id": 1, "active": true,} — a trailing comma makes this invalid JSON.
Common Use Cases
- Checking an API response before debugging further
- Verifying a config file is syntactically correct
- Teaching or learning correct JSON syntax
- Quick pre-flight check before pasting JSON into another tool
Frequently Asked Questions
Does this tool format my JSON too?
No, it only validates. Use the JSON Formatter tool if you also want to pretty-print or minify it.
Why does it say my JSON is invalid?
The badge is followed by a specific line and column where the parser stopped. Common causes are trailing commas, single quotes, or unquoted keys.
Is my data sent to a server?
No. Validation happens entirely in your browser using JavaScript's built-in JSON parser.
Does it support JSON5 or comments?
No, it validates strict JSON as defined by the JSON specification, which does not allow comments or trailing commas.
Can I copy the validation result?
Yes, the Copy Result button copies "Valid JSON" or the invalid status with its error detail.