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.
- No Upload: JSON is processed locally, 0 bytes sent
- Free: $0, no account, no sign-up
- Privacy: no account, nothing stored
- Modes: 3 – format/validate (2-space), minify, deep merge
Last updated: October 2026
JSON tool
Result
How it works
- 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.
- 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.
- Copy the result with the button above the output, or select it manually.
Frequently asked questions
Is my JSON sent to a server?
No. Formatting, validation and merging run entirely in your browser.
What happens when both objects have the same key?
JSON B's value wins; nested objects are merged recursively.
Can it minify JSON?
Yes. Minify strips the JSON down to a single line.
Everything runs locally in your browser using standard JSON parsing — your data is never uploaded or logged anywhere.