JSON Merge Tool
Combine multiple JSON objects with intelligent merge strategies
JSON Merge Tool
How it works:
- • Deep Merge: Recursively merges nested objects and concatenates arrays
- • Shallow Merge: Only merges top-level properties
- • Later objects override earlier ones for conflicting keys
What is JSON Merge?
The JSON Merge Tool combines multiple JSON objects into a single unified object. It supports both shallow and deep merge strategies, allowing you to control how nested objects and arrays are combined.
This is essential when working with configuration files, API responses, or any scenario where you need to consolidate data from multiple JSON sources into one cohesive structure.
Merge Strategies Explained
Deep Merge
Recursively merges nested objects at all levels. Arrays can be concatenated or replaced. Perfect for combining complex configuration files where you want to preserve nested structures.
Shallow Merge
Only merges top-level properties. Later values completely overwrite earlier ones for the same key. Ideal for simple overrides where nested objects should be replaced entirely.
How to Merge JSON Objects
- Paste your first JSON object into Object 1 editor
- Paste your second JSON object into Object 2 editor
- (Optional) Add a third object if merging three JSONs
- Select merge strategy - Deep merge or Shallow merge
- Click "Merge JSON" to combine the objects
- Copy the result - your merged JSON is ready to use
Common Use Cases
⚙️ Configuration Files
Combine base configuration with environment-specific overrides
🔄 API Responses
Merge data from multiple API endpoints into a single response
👤 User Settings
Consolidate default settings with user preferences
📦 Data Aggregation
Combine data from multiple JSON files into one unified dataset
Frequently Asked Questions
What's the difference between deep and shallow merge?
Shallow merge only combines top-level properties - if two objects have the same key, the entire value from the second object replaces the first. Deep merge recursively combines nested objects at all levels, preserving nested structures and only replacing individual leaf values. Use deep merge for complex configurations, shallow for simple overrides.
How are conflicting keys handled?
When the same key exists in multiple objects, the value from the last object takes precedence. This allows you to layer configurations, with later objects overriding earlier ones. For example, merge defaults → environment config → user overrides.
Can I merge more than 2 JSON objects?
Yes! You can merge up to 3 JSON objects at once. They are merged in order: Object 1 is merged with Object 2, then the result is merged with Object 3. This allows for layered configurations with clear precedence.
How are arrays handled during merge?
In deep merge mode, arrays are concatenated (combined). In shallow merge mode, the array from the later object completely replaces the earlier one. Choose your strategy based on whether you want to combine or replace arrays.
Can I merge JSON with different structures?
Absolutely! The merge tool intelligently handles objects with completely different structures. Non-overlapping keys from all objects will be included in the final merged result, while overlapping keys follow the precedence rules.
Is my data secure when merging JSON?
Yes! All merging happens 100% in your browser using JavaScript. Your JSON data never leaves your device and is never sent to any server, ensuring complete privacy and security for sensitive configuration data.
What happens to null and undefined values?
Null values in later objects will override previous values (null is a valid value). The merge tool follows standard JSON behavior where null is explicitly "no value" and will be included in the merged result.
Can I use this for merging package.json or tsconfig.json files?
Yes! This tool is perfect for merging configuration files like package.json, tsconfig.json, .eslintrc, or any other JSON-based config. Use deep merge to preserve nested configurations like "scripts", "dependencies", or "compilerOptions" while adding or overriding specific values.