What does this tool do?
Remove duplicate items from a JSON array, comparing either whole objects or a single key. Everything runs locally using JavaScript in your browser — nothing you paste or upload is ever sent to a server.
How to use this tool
- Paste your json array into the left-hand box.
- Fill in the dedupe by key (optional) field above the input.
- Click Remove Duplicates.
- Copy the deduplicated json from the output box.
Frequently asked questions
What happens if I leave the key field empty?
The whole item is compared for equality, so two items are only removed as duplicates if every field matches exactly.
What does the key field do?
Enter a key name (or dot path like user.id) and only that field is compared — the first item with each key value is kept, later ones are dropped.
Does it work on arrays of plain values, not just objects?
Yes, for arrays of strings or numbers, leave the key field empty and duplicates are removed by direct value comparison.