JAEN

List Comparer

Compare two lists and compute their intersection, union, and differences. Options let you control case sensitivity and how whitespace and blank lines are handled.

Input data is processed in your browser
Data is never sent to a server

Tool

0 lines
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What is the List Comparer?

This free tool compares two lists — email addresses, IDs, filenames, or anything else — and quickly identifies what they have in common and what’s unique to each.

It computes all four common set operations at once: intersection (in both), union (all unique items), only-in-A, and only-in-B, with a copy button for each. Options for case sensitivity, whitespace trimming, and blank-line handling let you compare messy real-world data flexibly.

How to Use

  1. Enter one item per line into "List A" and "List B".
  2. Toggle the options as needed — "Ignore case", "Trim whitespace", and "Skip empty lines".
  3. Click "Compare" to see four results — intersection, union, only in A, and only in B.
  4. Use the "Copy" button on any result card to copy just that result.

FAQ

What are intersection, union, and difference?

The intersection is the items present in both List A and List B. The union is all unique items from both lists combined. The difference ("only in A" / "only in B") is the items that appear in just one of the two lists. These are useful for comparing two datasets to find what they share or how they differ.

What happens if a list has duplicate items?

Duplicates are merged — each result shows each item only once, since the lists are treated as sets.

Does this work with very large lists?

Yes. The comparison runs entirely in your browser using a lightweight algorithm, so lists with tens of thousands of lines work fine.

Is my list data sent to a server?

No. All comparison happens entirely in your browser — nothing is sent anywhere.

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