JSON Formatter, free
Paste your JSON and it formats itself. Validate, repair and explore large files without sending your data.
- 100% free
- No signup
- Your JSON is never sent
- Files up to 100 MB
This JSON formatter tidies your content the moment you paste it, marks the line and column of every error and repairs broken JSON when you ask. It opens files up to 100 MB on a computer and keeps big numbers exactly as written. Your JSON is processed in your browser and is not sent to any server. It also works as a JSON beautifier, pretty printer, viewer and validator.
How to format JSON
Paste or drop your JSON
It formats itself when you paste. You can also open a .json or .jsonl file.
Fix or repair
If there is an error, you see its line and column. "Repair" fixes the most common problems and shows what changed.
Browse and take it with you
Search the tree, copy the path of a value, and copy or download the result.
What makes this formatter different
Your JSON is never sent
It is processed in your browser and never stored on a server, which makes it suitable for API responses and config files.
Large files
Opens up to 100 MB on a computer without freezing the tab, because the heavy work runs in the background.
Repairs, and tells you
Fixes quotes, commas and comments only when you ask, tells you what changed and lets you undo.
Exact numbers
Long integers and decimals keep their exact text. They are not rounded the way JSON.parse rounds them.
Browsable tree
Search keys and values and copy paths like $.users[0].email. It also works by touch on your phone.
JSON Lines
Detects files with one JSON per line and tells you exactly which lines fail.
What people use it for
Reading an API response
Turn one unreadable line into something you can review.
Fixing JSON from ChatGPT or Claude
Paste the block as it came, with ```json and odd quotes, and repair it.
Checking JSON Lines logs
Find which line is wrong in a log file.
Finding a value in a huge file
Find a key or value and copy its path for your code.
Why use this formatter
There are many free JSON formatters. These are the differences that matter.
- There is no save-to-server button: you share content inside the link.
- It is fully available in English and Spanish.
- It does not round big numbers.
- Ads stay outside the editor, so they do not get in the way while you work.
- It tells you what changed when it repairs, instead of changing it silently.
Frequently asked questions
How do I format JSON online for free?
Paste your JSON into the editor and it formats itself, with nothing to click. You can pick 2 spaces, 4 spaces or tabs, and you can also minify it or sort the keys. It is free and needs no signup.
How do I validate JSON and find the error?
When you paste it, the tool tells you whether it is valid and, if not, marks the exact line and column with the reason, such as an extra comma or an unquoted key.
Is it safe to paste my JSON here?
Your JSON is processed in your browser and is not sent to any server, nor to the analytics and ads the page loads. Even so, avoid pasting production tokens into any website if your company forbids it.
How do I fix broken JSON from ChatGPT or Claude?
Paste the text as it came and press "Repair". It fixes the ```json block, curly quotes, extra commas, comments and unquoted keys. Then it tells you what changed and lets you undo. Check the result, because badly damaged JSON may be repaired differently from what you expected.
What file size does it support?
It opens files up to 100 MB on a computer. On a phone the limit depends on its memory. Above 5 million characters, the editor shows a partial view and you browse the full file in the tree.
Does it keep big numbers intact?
Yes. Numbers keep their exact text, so 12345678901234567890 is not rounded, which does happen in tools that use JSON.parse.
What is JSON Lines and is it supported?
JSON Lines is a format with one JSON per line, common in logs and datasets. The tool detects it automatically, formats each record and tells you which lines are invalid.
How is it different from jsonformatter.org or JSONLint?
This tool is available in English and Spanish and does not store your JSON on a server. In 2025, the security firm watchTowr reported exposed data in saved JSON from jsonformatter.org and codebeautify. JSONLint and other tools remain good options for validation.
Is a JSON formatter the same as a JSON beautifier or pretty printer?
Yes. Format, beautify and pretty print all mean the same thing: laying out JSON with line breaks and indentation so it can be read. This tool does it as soon as you paste. The opposite is minifying, which puts everything on one line.
Can I keep several JSON files open and have them saved?
Yes. The + button opens tabs, each with its own JSON and settings, so you can compare or keep a sample at hand. They are saved automatically in this browser (nothing is uploaded to a server) and come back when you return. Files over 20 MB still work but are not kept after you close the browser. "Clear all" removes them from the browser.
Can I open this tool with my data already loaded, from a link or an AI?
Yes. Put the text in the link, after #, and the tool loads it on opening. That part of the link does not reach our server. Any person or AI assistant can write this link, with nothing to install.
To recommend the tool, the simple link is enough: https://soyjb.com/en/tools/json-formatter
Link format:
https://soyjb.com/en/tools/json-formatter#action=<action>&indent=<indent>&text=<URL-encoded>&url=<https-URL-encoded>- action: format, minify, validate, repair
- indent: 2, 4, tab
URL-encode the content and, if an AI writes the link, stay under 2,000 characters. Do not include passwords or production tokens.