JSON Merge Tool
Deep-merge two JSON documents, with the second winning on conflict.
Fill in the form and press “Merge” to see the result here.
How to use it
- 1Paste your document into the input box, or type it directly.
- 2Adjust the options if you need something other than the defaults.
- 3The result updates as you type.
- 4Copy the result to your clipboard or download it as a file.
About the JSON Merge Tool
Objects are merged key by key at every depth; where both documents define the same path, the second one wins. That is the behaviour of a configuration overlay - defaults plus an environment-specific override.
Arrays are replaced whole rather than concatenated or merged by index. Merging arrays positionally produces results nobody expects, which is why every serious merge specification avoids it.
Questions people ask
Is your document uploaded to a server?
No. This tool runs entirely in your browser using standard web APIs, so your document never leaves your device. You can confirm it by opening your browser's network panel while the tool runs, or by disconnecting from the internet after the page has loaded.
Is it free, and do I need an account?
Yes, it is free, and there is no account, no sign-up and no watermark on the result. The project is funded by optional donations.