Free tools / JSON Formatter & Merger

JSON Formatter & Merger

Pretty-print and validate JSON, or merge two JSON objects into one. Runs entirely in your browser — nothing is sent anywhere.

JSON tool

Result

How it works

  1. Format / Validate pretty-prints your JSON with 2-space indentation and points out exactly what's wrong if it isn't valid JSON. Minify strips it back down to one line.
  2. Merge deep-merges JSON A and JSON B: for any key that exists in both, B's value wins. Nested objects are merged recursively; arrays in B fully replace the matching array in A rather than combining them.
  3. Copy the result with the button above the output, or select it manually.

Everything runs locally in your browser using standard JSON parsing — your data is never uploaded or logged anywhere.