Turn nested JSON into a flat map of dot/bracket-notation keys — a.b.c, list[0]. Useful for spreadsheets, environment variables, feature flags, and config. Runs in your browser.
Each leaf value gets a single key built from its full path: nested object keys join with dots (user.name), and array elements use bracket indices (roles[0]). Empty objects and arrays are preserved as {} / [] so the structure round-trips. Flattening makes deeply-nested JSON easy to scan, diff, drop into a CSV column set, or map to UPPER_SNAKE env vars.