How to use it
- Paste your JSON into the input box.
- Click Format, Minify, or Validate.
- Copy the result.
Why use it
- Read messy JSON in seconds.
- Find syntax errors fast with clear messages.
- Minify data for APIs and configs.
- Keep your data private; nothing is uploaded.
- Free with no account or setup.
What is JSON?
JSON (JavaScript Object Notation) is a lightweight, human-readable format for storing and exchanging data. It is the de facto standard for REST and GraphQL APIs, configuration files, and storing structured data in databases and caches. Almost every modern web application exchanges JSON between its frontend and backend.
While JSON is designed to be easy for humans to read, real-world payloads are often minified or machine-generated, producing long single lines that are hard to scan. Pretty-printing (or formatting) that data with proper indentation makes it far easier to inspect, debug, and understand.
JSON vs. similar formats
| Format | Best for | Notes |
|---|---|---|
| JSON | APIs, configs, web data | Widest support; strings must be double-quoted |
| YAML | Human-written configs | Indentation-sensitive; often used for CI and infra |
| XML | Legacy systems, SOAP | Verbose; supports attributes and schemas |
| CSV | Tabular data | No nesting; good for spreadsheets |
Common JSON mistakes to avoid
- Trailing commas: a comma after the last item in an object or array is invalid in strict JSON.
- Single quotes: strings must use double quotes in JSON.
- Unquoted keys: object keys must always be wrapped in double quotes.
- Comments: JSON does not allow comments, unlike JavaScript or YAML.
- Bare NaN/Infinity: numbers must be finite, and unquoted text values are not allowed.
Pasting a JSON blob into a formatter that validates will catch these problems instantly and point to the exact location of the error, saving you from hunting through a long string of minified data.