JSON Merge
Merge multiple JSON objects into one
Input (Array of JSON objects)
Merged Output
What is JSON Merge?
Need to combine multiple JSON objects into one? This tool merges multiple JSON (JavaScript Object Notation) objects into a single unified object. Great for combining config files, merging API responses, or consolidating data from different sources.
As MDN Web Docs notes, merging JSON objects is super common in web development. Our tool supports both shallow and deep merge strategies, so you control how nested objects get combined. We follow the RFC 8259 JSON specification, so everything's valid.
Everything happens in your browser – your JSON never leaves your computer. Merge multiple objects instantly with one click.
What Makes This Tool Different
Deep & Shallow Merge
Choose deep merge (recursively merges nested objects) or shallow merge (overwrites nested objects). Pick what works for your use case.
Multiple Objects
Merge an array of JSON objects into one. We handle any number of objects, combining them in order with your chosen merge strategy.
Property Override
Later objects override earlier ones when properties conflict. Great for applying defaults first, then overriding with specific values.
File Upload Support
Got big files? Just upload them. Works great for merging those massive config files or API response arrays without copy-pasting.
Copy & Download
One click to copy, or download it as a file. Drop it right into your app – it's ready to go.
Syntax Highlighting
Both input and output get nice syntax highlighting. Makes it easy to verify the merged result looks right.
How It Works
Paste or Upload JSON Array
Paste an array of JSON objects into the left editor, or click "Upload" to load a file. The format should be like [{"key":"value1"},{"key":"value2"}]. Click "Sample" to see an example.
Choose Merge Mode
Select "Deep" for recursive merging of nested objects, or "Shallow" to overwrite nested objects entirely. The merged result appears automatically in the right panel.
Copy or Download
Review the merged JSON in the output panel. Click "Copy" to copy it to your clipboard, or "Download" to save it as a file.
When You'd Actually Use This
Config File Merging
Merge default configuration with environment-specific overrides. Deep merge preserves nested settings while allowing selective overrides.
API Response Combination
Combine multiple API responses into a single object. Useful when you need to aggregate data from different endpoints.
Data Consolidation
Merge JSON exports from different sources. Combine user data, settings, or preferences into unified objects.
Object Composition
Build complex objects by merging simpler ones. Great for creating default objects and then adding specific properties.
Common Questions
Is my JSON data stored?
Nope. Everything happens right in your browser. Your JSON never leaves your computer – we don't even see it.
What's the difference between deep and shallow merge?
Deep merge recursively combines nested objects, merging their properties. Shallow merge overwrites entire nested objects. For example, with two objects that both have an "a" property containing nested objects, deep merge combines the nested properties while shallow merge replaces the entire nested object.
What happens with conflicting properties?
Properties from later objects override properties from earlier objects. The last object in the array wins for conflicting keys.
Can I merge arrays?
We merge objects, not arrays. If you've got an array of objects, we'll merge those objects. Array properties within objects get overwritten, not merged.
What if objects have different structures?
The merge combines all properties from all objects. Properties that exist in one object but not others are preserved. The result contains all unique properties.
Does it work with invalid JSON?
Nah, you'll need valid JSON first. If something's broken, we'll show you an error. Try our JSON Validator or JSON Fixer to sort it out first.
Other JSON Tools You Might Need
Merging is just one JSON task. Here are other tools that work well together:
Need to learn more about JSON? Check out the official JSON.org website or the comprehensive guide on MDN.