JSON Formatter
Format, minify, and validate JSON online. Paste API responses or config files — all processing stays in your browser.
JSON
Pretty-print, minify, and validate JSON.
Recent Payloads
Payloads you format will appear here for quick access. Stored locally in your browser.
What this tool does
Pretty-print, minify, and validate JSON so you can inspect API responses, configs, and logs quickly.
Privacy
Your JSON never leaves this tab. Formatting and validation run entirely in your browser.
Use cases
- Debug API responses before integrating an endpoint
- Clean up copied JSON from logs or documentation
- Validate configuration files before deployment
Troubleshooting
Getting Unexpected token '<', "<!DOCTYPE"… is not valid JSON? The response is an HTML page, not JSON — that guide covers how to find which one and why.
Seeing a precision warning above, or wondering why a large id came back with different digits? Valid JSON, changed value measures which runtimes keep every digit and which do not.
Python reporting Expecting property name enclosed in double quotes? That one message covers single-quoted keys, unquoted keys, and a trailing comma.
Getting Unexpected end of JSON input? The payload ended where a value was due — that guide covers when it means an empty response body and when it means a truncated one.
A trailing comma in an object reports a position; in an array it reports none — that guide covers how to find the one you were not shown.
Seeing Bad control character in string literal? A real newline or tab landed inside a quoted value — that guide covers which characters are forbidden, and why the newlines in pretty-printed JSON are fine.
Need JSON Schema validation or custom formatting rules? Suggest a feature →