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 following industry standard merge algorithms, 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.
How to Use the JSON Merge
Follow these steps to merge multiple JSON objects. Each step uses the actual buttons and panels on this page.
Paste Array of JSON Objects or Upload
Paste an array of JSON objects into the left Input panel, or click Upload to load a file. Click Sample to see an example. Input format:
[{"subscriberId": "SUB-1001", "plan": "Unlimited 5G"}, {"dataUsage": 45.2, "carrier": "Verizon"}]Later objects override earlier ones when keys conflict. Follows standard merge algorithms per RFC 8259.
Choose Deep or Shallow Merge
Click Deep (default) to recursively merge nested objects – values from later objects merge into earlier ones. Click Shallow to overwrite nested objects entirely. The right Merged Output panel updates automatically.
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. Check out the ECMA-404 standard for more details.
What's the difference between deep and shallow merge?
JSON 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?
RFC 8259 Properties from later objects override properties from earlier objects. The last object in the array wins for conflicting keys.
Can I merge arrays?
MDN JSON 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: