Developer Tools
JSON Formatter
Paste raw JSON to format, validate and syntax-highlight it. Switch to Minify to compress it. All processing runs in your browser.
Format and validate JSON in three steps
No software to install. Works in any browser, on any device.
Paste your JSON
Drop raw or minified JSON into the input area.
Format or validate
Click to format with indentation, or validate to check for errors.
Copy the result
Copy the clean, formatted JSON ready to use.
JSON input
Format and validate
Prettify minified JSON and catch syntax errors simultaneously.
Error highlighting
Shows exactly where invalid JSON breaks.
Minify option
Collapse formatted JSON back to a compact single line for production.
About the JSON Formatter
JSON (JavaScript Object Notation) is a lightweight data format used by virtually every web API, configuration file, and database. Raw JSON from an API response or log file is often minified — all on one line with no indentation — which makes it nearly impossible to read. This tool reformats it into a structured, indented layout with colour-coded syntax highlighting.
The Format mode takes any valid JSON and outputs it with consistent indentation (2 or 4 spaces). Keys are highlighted in blue, string values in green, numbers in purple, booleans in amber and null in red. The Minify mode removes all whitespace and newlines, producing the smallest possible JSON for transmission.
The Validate button checks if your JSON is syntactically correct without formatting it. If the JSON is invalid, the error message shows exactly what is wrong and where.
Common mistakes that fail JSON validation: trailing commas after the last item in an array or object (valid in JavaScript but not JSON), single quotes instead of double quotes around strings, unquoted property keys, and comments (JSON has no comment syntax). This validator catches all of them.
JSON is used in API responses, configuration files (package.json, tsconfig.json, .eslintrc), database records in document stores like MongoDB, and data interchange between services. Being able to quickly format and validate a JSON blob is one of the most-used developer tasks — and this tool does it with no install required.
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Use itFrequently Asked Questions
What is JSON?
JavaScript Object Notation — a lightweight key-value data format. Standard for web APIs and config files. Human-readable and language-agnostic.
What makes JSON invalid?
Common mistakes: single quotes instead of double quotes, trailing commas after the last item, missing quotes around keys, or undefined/NaN values (not valid JSON types).
Formatting vs minifying JSON?
Formatting adds indentation for readability. Minifying removes all whitespace for compact transfer. Minified is smaller for networks; formatted is easier to read and debug.
Can I validate API responses with this?
Yes. Paste any JSON — from an API, a config file, or your own code — and the formatter checks validity and makes it readable.