JSON Formatter & Validator
Format, beautify, validate and minify JSON online. Clear error messages for invalid JSON. Private — nothing leaves your browser.
Validate and pretty-print JSON
Paste any JSON to format it with 2-space indentation, minify it for compact transfer, or simply check whether it's valid — parse errors are shown with the failing position selected in your input. Everything runs locally in your browser, so API responses, config files and payloads containing secrets never leave your machine.
Common gotchas that make JSON invalid: trailing commas, single quotes instead of double, unquoted keys, and comments (standard JSON allows none of these).
Frequently asked questions
Is my JSON uploaded anywhere?
No — parsing and formatting run entirely in your browser with JavaScript's built-in JSON engine. You can disconnect from the internet and the tool keeps working.
Why is my JSON with comments invalid?
Standard JSON forbids comments. Formats like JSONC/JSON5 allow them, but most parsers — including this one — follow the strict standard.