# JSON Merge

> Deep-merge several JSON documents, choosing how arrays and conflicts are resolved.

JSON merge combines several documents into one, recursing into nested objects so configuration layers accumulate rather than replacing each other wholesale. Later documents win on conflict, and arrays can be replaced, concatenated or unioned depending on what you need.

**URL:** https://convertto.tech/t/json-merge
**Category:** Data & Format Tools (https://convertto.tech/c/data-tools)
**Privacy:** Runs entirely in the browser; no upload
**Cost:** Free, no sign-up
**Last updated:** 2026-08-01

## Key facts

- **Privacy:** Runs entirely in your browser — nothing is uploaded
- **Cost:** Free, unlimited, no sign-up

## How to use

1. Enter or paste your json documents.
2. Choose the arrays.
3. Turn "Pretty-print" on or off as needed.
4. The result appears immediately — copy or download it.

## FAQ

### What is the difference between a shallow and deep merge?

A shallow merge replaces a nested object wholesale, so merging {a:{x:1}} with {a:{y:2}} loses x. A deep merge recurses and keeps both. Configuration layering almost always wants deep; state updates often want shallow.

### Which document wins a conflict?

The later one, by convention, because configuration is normally layered as defaults first and environment overrides last. Reversing the order reverses which value survives.

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