How to format JSON offline
- Open this page once while online. After that, you can disconnect.
- Paste your JSON into the editor.
- Click Format (2 Spaces) or Format (4 Spaces), or Minify.
- Fix any syntax error shown, then Copy the result.
Why format JSON offline?
The JSON you are debugging is often a raw API response, a log line or a config file - exactly the kind of data that contains bearer tokens, API keys, email addresses and internal hostnames. Several popular online formatters send your input to a server, and some have exposed what users pasted. An offline formatter removes that risk entirely.
How it works
The formatter uses your browser’s built-in JSON.parse and JSON.stringify. Nothing is transmitted and nothing is stored, so you can verify with your browser’s Network tab or simply by turning off your connection.
Common JSON errors
Strict JSON does not allow trailing commas, single-quoted strings, unquoted keys, comments, or values like NaN and undefined. If validation fails, look for these first - they account for nearly all errors in hand-edited JSON.
Frequently asked questions
Is my JSON uploaded?
No. All parsing and formatting happens in your browser.
Does it really work without internet?
Yes. Once the page is loaded, the formatter needs no network connection.
Can I minify JSON too?
Yes. The Minify button strips all whitespace for the smallest possible payload.