List Comparison Tool

How to use

1. 1Paste your first list into List A and your second list into List B. Use the sample buttons (Email lists, Keyword lists, User IDs, Tag lists) to load a working example.
2. 2Pick how each list is split: one item per line is the most common, comma-separated covers spreadsheet exports, and whitespace-separated handles single-line inputs of IDs or tags.
3. 3Adjust comparison rules. Keep 'Trim whitespace' on to ignore stray spaces, 'Ignore blank items' on to drop empty rows, and turn on 'Case sensitive' only when capitalization should make 'Apple' different from 'apple'.
4. 4Read the five result panels: Common to both, Only in A, Only in B, In either list, and In exactly one list. Each panel shows a count and a copy button so you can grab just the slice you need.
5. 5Use Swap A and B to flip the lists, Clear both to start over, or toggle 'Sort each result alphabetically' off if you want results in the order they appeared in your source lists.

About this tool

List Comparison Tool takes two lists and shows exactly how they overlap. Paste List A and List B, pick how each list is split (one item per line, comma-separated, or whitespace-separated), and the tool reports five result groups at once: items common to both lists (the intersection), items only in List A, items only in List B, every unique item across both lists (the union), and items present in exactly one list (the symmetric difference). Each group is separately copyable so you can grab the slice you need without rebuilding the comparison. Three small but important controls keep the results matching real-world usage: trim whitespace removes leading and trailing spaces so 'alice@example.com' and ' alice@example.com ' compare equal, ignore blank items drops empty rows that creep in from copy-paste, and the case-sensitive switch lets you decide whether 'Apple' and 'apple' count as the same item. Each result list can be sorted alphabetically with a locale-aware natural sort (so file2 lands before file10), or kept in source order if you want to preserve the order the items appear in the lists you pasted. The tool also reports per-list stats: how many items each side started with, how many were unique after deduplication, and how many duplicates within a single list were collapsed before the comparison. Useful for reconciling two email subscriber exports, finding keyword gaps and overlaps between two SEO lists, comparing two ID exports from a database, finding which tags are unique to one CMS export versus another, spotting missing rows after a data migration, and any time you have two lists and want to know what they share, what they don't, and which side an item came from. Comparison runs entirely in your browser using JavaScript Sets, so the lists you paste here, including any internal IDs or customer email addresses, never leave your device.

Free to use. Works in your browser. No signup, no login.