Format · Indent · Copy
Format JSON Online
Updated: June 2026
When an API hands back a single dense line of JSON, the fastest way to read it is to format it. Formatting re-indents the data so every object, array and value sits on its own line — turning an unreadable blob into a structure you can scan in seconds.
Free · No upload · Instant in the browser
Why formatting matters
Raw JSON from a server is almost always minified: whitespace costs bandwidth, so it is stripped before transport. That is great for machines and terrible for humans. A 4 KB response printed as one line is impossible to follow, and the moment you need to find one nested field you are scrolling sideways through a wall of braces and commas.
Formatting reverses that. It inserts newlines after every comma and indents each level of nesting, so the shape of the data becomes visible. Object keys line up in a column, array items stack vertically, and the depth of a value is shown by how far it sits from the left margin. The data is identical — only the presentation changes.
How to format JSON online
- Copy the JSON from your terminal, browser network tab, log file or code editor.
- Paste it into the input panel of the formatter.
- Pick an indent width — 2 spaces is the web default, 4 spaces is common in Python and Java shops, and tabs suit teams that configure width per editor.
- Read the formatted result on the right, then copy or download it.
Because the tool parses your text into a real value before re-printing it, the output is guaranteed to be valid, canonical JSON. Any duplicate keys are resolved the way the JSON spec dictates, numbers are normalised, and the result will re-parse cleanly in any language.
Choosing an indent size
| Indent | Best for |
|---|---|
| 2 spaces | Web configs, package.json, JavaScript and TypeScript projects |
| 4 spaces | Python, Java and .NET ecosystems, deeply nested documents |
| Tab | Teams that set display width in the editor rather than the file |
There is no universally correct choice — pick whatever matches the file you are pasting into. If you are formatting for a code review, match the indentation your repository already uses so the diff stays clean.
Everything stays in your browser
Online formatters have a privacy problem: many of them send your JSON to a server to do the work. If that JSON contains API keys, customer records or internal identifiers, you have just leaked it to a third party. This formatter never does that. The parsing and re-printing happen entirely in JavaScript on your own machine, so the data on the page never travels across the network. You can confirm it by opening your browser's network tab — there is no request when you format — or by disconnecting from the internet and watching the tool keep working.
That local-first design also makes it fast. There is no round trip to wait for, so even large documents format the instant you stop typing.
Frequently asked questions
How do I format JSON online for free?
Paste your JSON into the input box, choose an indent size and the formatted version appears immediately. It is free, needs no account, and runs entirely in your browser.
Will formatting change my data?
No. Formatting only adds whitespace and line breaks. The keys, values and structure are identical — the output re-parses to exactly the same value.
Is there a size limit?
There is no hard limit. Because the work happens locally, you are only bounded by your device memory. Documents of several megabytes format comfortably.
Is my JSON uploaded anywhere?
No. All formatting runs in JavaScript on your machine. Nothing is sent to a server and the tool works offline once loaded.