What is it?
The JSON Validator checks whether JSON data is written correctly. If it is not, it shows the exact line and column and explains the mistake in plain words, and Fix common mistakes repairs the usual ones in one tap.
Who is it for?
Developers whose app says “Unexpected token”, testers checking API responses, people editing config files (package.json, settings.json, manifest.json), and students learning JSON.
How to use it
- Paste your JSON.
- Read the result: valid, or the line and column of the first error.
- Tap Fix common mistakes to repair trailing commas, single quotes, comments and similar, then choose the Indent (2 spaces, 4 spaces or Tab) for tidy output.
Worked example
{"name": 'Asha', "age": 30,} has two mistakes: single quotes around Asha and a trailing comma before }. Fix common mistakes turns it into {"name": "Asha", "age": 30}.
Your code stays in your browser; nothing is sent to us.
Errors and how to fix them
- Line … column …: go to that line; the real mistake is often at the end of the line above (a missing comma).
- Could not fix it automatically. Line …: the problem isn’t a common one, such as a missing closing bracket far away or text pasted twice. Fix it by hand at the line shown.
- Valid here, but my app still fails: the app may need a different structure (an array instead of an object) or specific field names.
- Huge files are slow: validate a smaller piece first to find the problem area.
Open the tool: JSON Validator
Still stuck?
Contact support. Tell us which tool or page you were using, what you tapped, what you saw, and your phone or computer and browser (for example: Android phone, Chrome). We reply by email.
Questions, or an error not listed here?
Tell us in the comments: what you were doing, the exact message you saw, and your device and browser. We read every comment and add new fixes to this article.