JSON Formatter for Developers

Make a wall of JSON readable, and a malformed one diagnosable, in under a second.

Tools for engineers who would rather not context-switch into yet another tab to validate a JWT or generate a UUID. Everything runs in your browser, your payloads never leave the machine, and the pages load fast enough that you can leave them open in a sidebar while you debug.

Open the JSON Formatter →

What it does for Web and API developers

How to use it

  1. Open the tool and paste a JSON blob (from your terminal, from a curl, from a log line).
  2. Pick 2-space or 4-space indentation. The tree expands automatically; click any key to fold its subtree.
  3. If the JSON is malformed, the parser stops at the first error and points at the line and column, so you do not have to count braces by eye.

Other tools Developers reach for

JWT DecoderSee the header, payload and signature of a JSON Web Token without trusting a third party.UUID GeneratorProduce v4 UUIDs in bulk, with the option to copy one straight to the clipboard.Base64 Encoder / DecoderRound-trip a string or a file between bytes and base64 without uploading either.URL Encoder / DecoderPercent-encode or decode URL components with the right rules per part of the URL.Unix Timestamp ConverterConvert epoch seconds or milliseconds to a human date and back, with timezone awareness.

Common questions

The payload is huge. Can I format it here without pasting the whole thing?

Paste a representative slice - one object from the array, one page of the response - and validate the shape first. The formatter works on what you paste, so a truncated paste tells you nothing about the field you actually care about, and a genuinely large payload belongs in your editor or a command-line tool.

Is it safe to paste a response that contains an API key or a session token?

The parsing happens in your browser, so nothing is uploaded. That is not the same as harmless: a token you paste is a token sitting in a clipboard history, a screen share and possibly a screenshot. Redact the secret before you paste, or rotate it afterwards if the token was live.

Why does one payload parse and another nearly identical payload fail?

Look for the difference you cannot see: a trailing comma, a single-quoted key, an unquoted brace, a byte-order mark at the start of the file, or a log line glued to the front of the JSON. Parsers fail at the first character that is not valid, which is usually not the character you are staring at.