JSON Formatter & Validator
Paste JSON to make it readable, check it for syntax errors or minify it. Errors show the line and column where your browser reports them, with a plain-language hint.
0 characters · 0 bytes (UTF-8)
Up to 5 MB. Press Ctrl + Enter (⌘ + Enter on Mac) to format.
Empty
Your JSON is processed in your browser and is not sent to our servers.
How to use JSON Formatter & Validator
- 1
Paste your JSON
Paste or type JSON into the input, up to 5 MB. “Load example” fills in a sample to try.
- 2
Format, minify or validate
Format with 2 spaces, 4 spaces or tabs, minify to remove formatting whitespace, or just check that it’s valid. Errors point to the line and column when your browser reports them.
- 3
Copy or download
Copy the result, download it as a .json file, or move it back into the input to keep working.
Frequently asked questions
How does validation work?
Your JSON is checked with your browser’s built-in strict JSON parser. If it’s invalid you’ll see the browser’s message, the line and column when the browser provides them, and a hint about the likely cause. It checks syntax only, not whether the data matches a schema.
Why is my JavaScript object not valid JSON?
JSON is stricter than JavaScript. Property names and strings must use double quotes, and JSON doesn’t allow trailing commas, comments, single quotes, undefined, NaN or Infinity. Fix those and it will validate.
Does formatting or minifying change my data?
No. Only the whitespace between values changes. Keys stay in their original order, and numbers, strings and escape sequences are kept exactly as written — even very large numbers and repeated keys.
Can I choose the indentation?
Yes. Choose 2 spaces, 4 spaces or tabs. Changing it re-formats the output straight away.
Is there a size limit?
Yes, 5 MB of text, so a huge paste can’t freeze your browser tab. For larger files, use a code editor or a command-line tool.
Is my data sent to a server?
No. Formatting and validation happen in your browser, so your JSON stays on your device.