JSON Merge — Deep Merge Multiple Objects

Deep merge two or more JSON objects into one with intelligent conflict resolution. Handles nested objects, arrays, and type conflicts. 100% client-side.

Left JSON (A)0 chars

Right JSON (B)0 chars

Output

—

🛡️Zero server logs. Merging runs 100% inside your browser.

JSON Merge — Deep Merge Multiple Objects

Deep merge two or more JSON objects into one with intelligent conflict resolution. Handles nested objects, arrays, and type conflicts. 100% client-side.

🔒 Client-side only⚡ Web Worker processing🌐 Works offline🛡️ Zero server logs

How to Use

Paste the JSON objects to merge into the input area (one per line or as an array).
Select the merge strategy (deep merge, overwrite, or array concat) and click Merge.
Copy the merged result for use in configuration or data aggregation.

Frequently Asked Questions

Questions about this tool? We've got answers.

What merge strategies are available?

Deep merge (recursive object merge), overwrite (later values replace earlier ones), and array concatenation. Conflicting types are handled with clear priority rules.

How are conflicts resolved?

When identical keys have different types, the later object's value wins. Arrays can be concatenated or replaced depending on the chosen strategy.

Is my data sent to a server?

No. All processing runs 100% inside your browser via a Web Worker.

Automated E2E Test Suite Logs

Our build systems validate edge-case processing under extreme conditions before each deployment.

Stability

100.0%

Passed

23/23

Env

V8-Sandbox

Engine: Vitest RunnerUpdated: 2026/6/11 00:18:12📦 Download Test Datasets

PASSmergeJsonObjects should merge two documents with override

PASSmergeJsonObjects should deep merge nested objects

PASSmergeJsonObjects should throw when both inputs are empty

PASSmergeJsonObjects should throw on invalid JSON in left

PASSmergeJsonObjects should throw on invalid JSON in right

PASSmergeJsonObjects should throw on non-object input

PASSmergeJsonObjects should merge with empty right side

PASSmergeJsonObjects should merge with empty left side

PASSJsonMergeTool renders Merge button

PASSJsonMergeTool renders Left JSON and Right JSON labels

PASSJsonMergeTool shows Load URL button

PASSJsonMergeTool renders three textareas (left, right, output)

PASSJsonMergeTool shows privacy strip

PASSJsonMergeTool shows error toast on Merge with both inputs empty

PASSJsonMergeTool shows Clear toast on Clear All click

PASSJSON Merge Worker Standard merge operations should merge two documents

PASSJSON Merge Worker Standard merge operations should merge nested objects

PASSJSON Merge Worker Standard merge operations should propagate requestId correctly

PASSJSON Merge Worker Boundary Conditions & Error Handling should return error for invalid JSON

PASSJSON Merge Worker Boundary Conditions & Error Handling should return error for empty input

PASSJSON Merge Worker Boundary Conditions & Error Handling should return error for non-object input

PASSJSON Merge Worker Boundary Conditions & Error Handling should return error for array in right input

PASSJSON Merge Worker Performance Benchmark should merge large objects within acceptable limits

⏱️ 0.18ms📦 1.5KB🎚️ Max Nesting: 3🌿 AST Nodes: 48🛡️ V8 Heap: Healthy

$ codecaven-validator --scope=tool● CLUSTER COMPLIANT

Tool Changelog & Updates

1.0.02026-06-10

Feature: Initial release