JSON Merge

What is JSON Merge?

JSON Merge is a free, browser-based tool that helps you get the job done quickly. Deep-merge two or more JSON documents with conflict policy. It's built for speed and privacy: Everything runs locally in your browser — your data is never uploaded to a server. No sign-up, no installs, and no daily limits.

Used by

• Data engineers
• Backend developers
• API developers
• Data analysts

Recommended workflow

1. 1

   Prepare the input

   Use this tool as the focused step in a larger browser-based workflow.

2. 2

   Run JSON Merge

   Review the preview, copy or download the result, and keep everything local in your browser.

3. 3

   Next recommended tool

   JSON Compare: Side-by-side diff of two JSON documents with structural alignment.

   Open tool
4. 4

   Then continue with

   JSON Formatter: Pretty-print, minify, and indent JSON safely.

   Open tool
5. 5

   Then continue with

   JSON Validator: Validate JSON syntax with helpful error messages.

   Open tool

Frequently asked questions

How do I use JSON Merge?

Paste or drop your data into the workspace, adjust the options to fit your data, then copy or download the result. Deep-merge two or more JSON documents with conflict policy.

Is my data uploaded or stored anywhere?

No. Everything runs locally in your browser — your data is never uploaded to a server. Nothing is sent to a server, so it's safe to use with private or sensitive data.

Is JSON Merge free?

Yes — it's completely free with no account, no sign-up, no watermark, and no daily usage limits.

What's the maximum file size?

There's no hard limit imposed by the tool. Because processing happens in your browser, the practical ceiling is your device's available memory — most everyday files work instantly.

Do I need to install anything?

No installs and no extensions — it runs entirely in your web browser and even works offline once the page has loaded.