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LocalThis runs in your browser. Nothing you paste is sent anywhere.

JSON -> READABLE · Local tool

JSON Formatter and Validator

Format, beautify, validate and read JSON, and find the line that broke it.

Last updated

How do I format JSON without sending it to a server?

filetity's JSON formatter parses and re-prints JSON inside your browser tab, so the payload never leaves the machine. That is the point when the JSON is an API response, a token, or anything from work that should not be pasted into a stranger's website. Broken JSON gets the line and column where parsing stopped, not the word invalid on its own. The output can be indented with two spaces, four spaces or tabs, or minified back onto a single line. Once the page has loaded it keeps working with no network connection, so it is still there on a plane or behind a locked-down network.

  1. 01 / Your device

    the file stays here

  2. 02 / Browser memory

    the work runs locally

  3. 03 / Back to you

    saved on this device

When you would use this

Situations, not settings.

An API response that arrived on one line
Minified JSON is unreadable by design. Formatting shows the structure without pasting it into someone else's site.
JSON that will not parse
The error points at the line and position that broke it, rather than saying invalid.
Data you should not paste anywhere
Tokens, customer records and internal payloads stay in the tab. Nothing is sent.

How it works / no cloud

A conversion engine, not an upload form.

Your browser already has a JSON parser, so filetity uses it and adds the part it does not give you: when the document will not parse, the text is scanned to find the exact character where it stopped being valid. Nothing you paste leaves the page.

  • Offline ready
  • Installable app
  • No file limit queue

Straight answers

No accordion. Nothing hidden.

Is it free?
Yes, with no watermark and no page limit.
Does it need an account?
No. There is no account system.
Is my file processed on my device?
Yes. The file is read by your browser and never uploaded. There is no server to send it to.
What formats are supported?
JSON in. Formatted JSON out, with 2 spaces, 4 spaces, tabs, or minified.
What are the limits?
No size limit beyond what your browser will hold in a text box. Very large documents are better handled as a file by a local tool.
Does it work on mobile?
Yes, on any modern mobile browser. Large files are limited by the memory the phone gives the browser.
Does it work offline?
Yes, after you have used it once. Your browser keeps what the tool needs, so it then works with no network connection.
Is my data sent to a server?
No. There is no server. This matters more here than anywhere else on the site, because the JSON people need formatted is usually an API response with a key, a token or a customer record in it.
Why does it tell me a line number when other formatters just say invalid?
Because the line number is the reason you opened a formatter. Browsers give a position for some malformed documents and nothing useful for others, so when the browser will not say, the text is scanned to find where it stopped parsing.
Does sorting keys change my data?
It reorders object keys alphabetically at every depth, which JSON treats as meaningless, and leaves arrays exactly as they are, because array order is data. Sorting is off unless you ask for it.
Is a JSON beautifier the same as a formatter?
Yes. Beautify, prettify, format and pretty-print all describe the same thing: taking JSON that arrived as one unreadable line and laying it out with indentation so a person can follow it. This page does that, and does the reverse too if you pick Minified.
Can I use this just to check whether my JSON is valid?
That is what it does as you type. Valid JSON shows a confirmation and the byte counts; invalid JSON gets the line and column where it broke and what was expected there. You do not have to press anything, and nothing is sent anywhere to check it.

Keep working locally

7 available · more coming