Format, beautify and validate JSON with syntax highlighting
A JSON formatter (also called a JSON beautifier or pretty printer) takes raw, minified or messy JSON and turns it into a clean, indented, human-readable structure. JSON — JavaScript Object Notation — is the standard data format for REST APIs, configuration files and data exchange between services, but in production it usually travels as a single compressed line that is almost impossible to read. This tool parses your JSON, validates the syntax and re-prints it with consistent indentation and syntax highlighting, so you can instantly see the structure of nested objects and arrays.
Everything runs locally in your browser: the JSON you paste is never uploaded to any server, which makes it safe to format API responses containing tokens, customer data or other sensitive information. If the input is invalid, the formatter pinpoints the syntax error — a missing comma, an unquoted key, a trailing bracket — so you can fix it in seconds instead of hunting through thousands of characters.
No. The formatter runs 100% in your browser using JavaScript. Your data never leaves your device, so it is safe to paste API responses that contain tokens, passwords or personal data.
Validating checks that the text follows the JSON specification; formatting re-prints valid JSON with readable indentation. This tool does both at once: if your JSON is invalid you get a descriptive error, and if it is valid you get a beautified version.
The most common causes are trailing commas, single quotes instead of double quotes, unquoted property names and comments — none of which are allowed in strict JSON. The error message tells you where the parser stopped so you can fix the exact spot.
Yes. Because processing happens locally there is no upload limit — performance depends only on your device. Files of several megabytes format in well under a second in a modern browser.
JSON Minifier · JSON Validator · JSON to CSV · JSON ↔ YAML · JSON Flatten · JSON Compare