Format, validate, and minify JSON — catch errors instantly.
JSON Formatter is a free online tool that formats, validates, and minifies JSON data instantly. It catches syntax errors on the fly with clear error messages, making it an essential tool for any developer working with APIs, configuration files, or data interchange. The formatter mode transforms compact or single-line JSON into a beautifully indented structure with 4-space indentation, making nested objects and arrays easy to read and navigate. The minify mode does the opposite — compressing formatted JSON into the smallest possible representation by removing all whitespace. JSON validation happens automatically as you process your data. If your JSON contains syntax errors — missing commas, unquoted keys, trailing commas, or mismatched brackets — the tool identifies the exact error and its location. This saves significant debugging time compared to manually searching through large JSON documents. Everything runs entirely in your browser. Your JSON data is never sent to any server, making it safe for API responses containing user data, configuration files with credentials, and any sensitive data structures. There are no file size limits, no usage caps, and no account required. The tool also displays useful statistics including the number of keys, nesting depth, and data size. Common use cases include formatting API responses for debugging, validating JSON configuration files, preparing JSON data for documentation, minifying JSON for storage optimization, and inspecting webhook payloads. For related functionality, check out the JSON Schema Generator which creates validation schemas from your JSON data, and the CSV/JSON Converter for transforming between data formats.