JSON Combiner
Combine two JSON files into one
JSON File 1
JSON File 2
Combined JSON
JSON Combining Examples
Paste two JSON files — one in each input editor — and the tool combines them automatically:
Merging two user objects
Click Sample to load example JSON into both editors and see the combined result instantly.
What Is a JSON Combiner?
Working with JSON often means dealing with data spread across multiple files — config fragments, API responses, partial records. A JSON combiner merges two inputs into one. Two objects get shallow-merged (keys from File 2 override File 1), two arrays get concatenated, and mixed types get wrapped in an array. The format follows RFC 8259 and this tool gives you a quick dual-input editor right in your browser.
Paste your first JSON into the top-left editor and your second into the bottom-left editor (or use Upload on each panel). The right panel auto-combines both inputs into one output. Everything runs in your browser — nothing is sent to a server. For formatting the result, use JSON Formatter. For validating, use JSON Validator.
How to Use This Tool
Paste or Upload JSON
Paste your first JSON file into the top-left editor and your second file into the bottom-left editor. Each panel has its own Upload button so you can load .json files individually. Use Sample to load example data into both editors at once.
Review Combined Output
The right panel auto-combines both inputs. Objects are shallow-merged, arrays are concatenated. For comparing differences first, try JSON Diff. For deep merging, try JSON Merge.
Copy or Download
Use Copy or Download to save the combined JSON. Need to minify it? Use JSON Minifier. Want to sort the keys? Use JSON Sort.
Where JSON Combining Helps
API integrations, config management, data migration — all common scenarios where you need to merge two JSON files quickly. Tools like jq handle this from the command line, but this tool gives you a visual dual-editor that runs instantly in the browser. Great when you just need to combine two payloads without writing a script.
When working with JSON in JavaScript or Node.js file APIs, you can programmatically merge JSON. But for quick one-off tasks, this browser tool is faster. For editing the result afterwards, use JSON Editor. For exporting to spreadsheets, use JSON to CSV.
Frequently Asked Questions
Is my data private?
Yes. Combining runs entirely in your browser. No data is sent to any server.
What happens when both objects have the same key?
File 2 wins. The combiner does a shallow merge, so if both objects share a key, the value from File 2 overwrites the one from File 1. This follows the same behavior as Object.assign() or the spread operator in JavaScript.
How does it handle arrays?
If both inputs are arrays, they get concatenated into a single array. If one is an object and the other is an array (or vice versa), both values are wrapped together in a new array.
Is the output valid JSON?
Yes. The combined output is always valid JSON. You can verify it with our JSON Validator if you want to double-check.
Can I upload .json files?
Yes. Each input panel has its own Upload button. Click it to select a .json file for that panel. File 1 goes into the top-left editor, File 2 into the bottom-left editor.
Related Tools
Learn more: json.org, RFC 8259, MDN JSON, jq, Node.js fs.