JSON Formatter

Format, validate, minify, and explore JSON data entirely in your browser. Paste raw JSON from API responses, config files, or databases and instantly see it pretty-printed with syntax highlighting, compacted for transmission, or rendered as an interactive tree.

The validator pinpoints the exact line and character of any error with plain-English explanations. Supports JSONC (JSON with comments), detects common JavaScript-object mistakes like unquoted keys and trailing commas, and handles inputs up to hundreds of kilobytes.

Typical use cases: a backend engineer debugging a 500-response body that contains a deeply nested error object and needs to see the structure before filing a ticket; a mobile developer comparing two API responses to spot which field changed between staging and production; a data analyst pasting a row from a logs table to pick out one nested value quickly. The tree view is particularly helpful for the third case — click-to-expand keeps the full payload collapsed while you drill into the one field you care about.

Zero external libraries — everything uses native JSON.parse() and JSON.stringify() plus a CodeMirror-based editor for the syntax highlighting. Performance is bounded by the browser's own JSON parser, which in V8 (Chrome/Edge) can ingest multi-megabyte payloads in tens of milliseconds. Edge case worth knowing: JSON Number precision tops out at IEEE 754 doubles (15–17 significant digits), so a 19-digit integer like a Twitter snowflake ID will silently lose precision unless you keep it as a string — this is a JSON spec limitation, not specific to this tool.

Compared to pasting into `jq` on the command line, the formatter gives a visual tree and live error highlighting without needing a CLI install or knowing jq's query syntax. Compared to online formatters that POST your JSON to their server, this one keeps production payloads (which may contain keys, tokens, or PII) on your machine only.