JSON Formatter & Validator — Free Online Tool
Format, pretty-print, and validate JSON in your browser. Fast, private, and secure.
How to use
- Paste raw JSON into the left box.
- Click Format or press ⌘/Ctrl+Enter.
- Review the formatted output on the right and Copy output.
- Use Clear to start over, or Share to create a prefilled link.
Common pitfalls
- Single quotes: JSON requires
"double quotes, not'. - Trailing commas: remove the last comma in arrays/objects.
- Comments: JSON does not support
//or/* */comments. - Unescaped characters: escape inner quotes like
"Alice said: ""Hi!""". - Numbers: very large integers may lose precision in JavaScript.
Example
{"name":"Alice","age":30,"hobbies":["hiking","chess"],"address":{"city":"Denver","zip":"80202"}}{
"name": "Alice",
"age": 30,
"hobbies": [
"hiking",
"chess"
],
"address": {
"city": "Denver",
"zip": "80202"
}
}About this tool
Pretty-print and validate JSON entirely in your browser. Paste raw JSON, catch errors, and copy a clean, indented output.
No data is uploaded. Perfect for API responses, configs, and logs.
FAQ
Is formatting done locally?
Yes. All parsing and formatting run entirely in your browser; nothing is uploaded.
Why do I get “Unexpected token … at position …”?
That means the JSON is invalid at that character index. This tool maps it to line and column and highlights the spot so you can fix it quickly.
Are comments or trailing commas allowed?
No. Standard JSON does not allow comments or trailing commas. Remove them before formatting.
Is there a size limit?
Only your device memory limits extremely large inputs. For huge files, try formatting in chunks.
Can I share a prefilled example?
Yes. Use the Share button. Your JSON is embedded in the URL query (?q=...).