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Compare two lists to find unique and common items instantly.
🔒 100% client-side — lists are compared locally. Duplicates within each list are collapsed by default.
Comparing two lists is a surprisingly common task: which email addresses are in spreadsheet A but not B, which files exist in one folder but not another, which SKUs appeared in last month's report but not this one. Doing it by eye is hopeless for anything beyond a handful of items. This tool compares two lists line-by-line and splits them into the four sets that fully describe how they differ.
By default the tool trims whitespace from each line (so "apple " matches "apple") and compares case-insensitively (so "Apple" matches "apple"). Turn off trimming if leading spaces matter to you, and turn on case sensitivity if SKU001 and sku001 are genuinely different items. Each result set has its own Copy button so you can paste it straight into a spreadsheet or another tool.
Within a single list, duplicates are collapsed — apple appearing three times in list A counts as one item. This matches how set operations work mathematically and is almost always what you want when diffing. If you need to know that A had three copies and B had one, preprocess the lists with a line-counter first, then diff the unique keys.
The List Diff & Intersection Checker handles list diffdirectly in your browser. Paste or type your input, and the tool processes it instantly — no upload, no signup, no waiting. It's built for the moments when you need a quick transformation and don't want to leave your workflow.
Because the tool runs client-side, it's fast and private. Your text never touches a server, which makes it safe for sensitive content. The interface is keyboard-friendly and works on any device with a modern browser.
Common uses: people reach for this tool when they need to use a compare two lists online find differences, list intersection and union calculator, find items in one list not other, or deduplicate and diff two text lists.
Browser-based tools like this one have a few real advantages over installed software or manual methods:
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