How to Compare Two Lists Online

Q: How do I find what's in one list but not another?

Paste both lists into the Compare Two Lists tool . A Only shows everything in your first list that isn't in the second. B Only shows the reverse.

Q: What if I need to see how lines changed, not just which lines exist?

Use the Text Diff tool . It shows exactly which characters changed within each line, like a code diff. This compare tool is for set operations on lists. Text Diff is for when the content within individual lines matters.

To compare two lists, you need to know what's different between them. Maybe it's customers from two different months, products in two systems, or two versions of the same spreadsheet that got edited independently. Whatever it is, paste them here and you'll have your answer before you finish reading this page.

Quick answer

To compare two lists, paste each one into a list comparison tool - it instantly shows which items appear in both lists, which are unique to each one, and the combined set of everything across both. This works for names, emails, product IDs, or any line-separated data from Excel, CSV, or plain text, and runs entirely in your browser.

Free and instant. No sign-up needed.

Open Compare Tool →

How it works

Paste your first list into List A. One item per line. Blank lines get ignored, so don't worry about those.
Paste your second list into List B. Names, emails, product IDs, URLs, whatever you've got. One per line.
Look at the four output panels. They update as you type or paste:
- A Only - items in List A that aren't in List B.
- B Only - items in List B that aren't in List A.
- A ∩ B (Intersection) - items that appear in both.
- A ∪ B (Union) - every unique item from either list.
Copy whatever you need. Each panel has a Copy button. Click it and paste wherever.

Which result do you actually want?

This is the part people skip and then wonder why the output isn't what they expected.

A Only and B Only are for finding what changed. If you're comparing this month's customer list to last month's, A Only shows who dropped off and B Only shows who's new (or the reverse, depending on which list is which).
Intersection is for finding common ground. Same contacts in two CRMs. Same SKUs in two inventory systems. Products that appear in both suppliers' catalogues.
Union is for merging. You want one clean, deduplicated list of everything. Two keyword lists, two team rosters, two supplier catalogues combined into one.

Options worth knowing about

The defaults work for most cases, but here's what you can change:

Case Sensitive is on by default. Turn it off if "Apple" and "apple" should count as the same thing.
Ignore Leading/Trailing Spaces is also on by default. It strips whitespace from the start and end of each line. Useful when different systems export data with different padding.
Ignore Extra Spaces collapses multiple spaces into one. Catches "John Smith" vs "John Smith" type mismatches.
Ignore Leading Zeros treats "007" and "7" as the same value. Useful for IDs that different systems store inconsistently.

When you need character-level differences instead

This tool works at the line level: it tells you which lines exist in each list, not how the text within individual lines has changed. If you need to see exactly which words or characters were edited (think: comparing two versions of a config file, or spotting edits in a paragraph), use the Text Diff tool. It shows character-level changes highlighted inline, the same way a Git diff works.

Comparing more than two lists?

Multi-List Compare handles 3 to 8 lists at once, with a Venn diagram.

Try Multi-List Compare →

Frequently Asked Questions

How do I find what's in one list but not another?

Paste both lists into the Compare Two Lists tool. A Only shows everything in your first list that isn't in the second. B Only shows the reverse.

What is the difference between list intersection and union?

Intersection (A ∩ B) is what's in both lists. Union (A ∪ B) is everything from either list, without duplicates. If List A has apples and bananas, and List B has bananas and cherries: the intersection is 'bananas' and the union is 'apples, bananas, cherries'.

Can I compare more than two lists at once?

Yes. The Multi-List Compare tool handles 3 to 8 lists at once. It shows all the set combinations and draws a Venn diagram so you can see the overlaps visually.

How do I compare lists without matching uppercase and lowercase?

Open Options and uncheck Case Sensitive. 'Apple', 'APPLE', and 'apple' will all be treated as the same item.

Why are there differences when the lines look identical?

Almost always invisible characters. Non-breaking spaces, zero-width spaces, and carriage returns look like nothing but break comparisons. Paste your list into the Invisible Character Detector to see what's actually in there. Then use the Data Cleaner to strip them out.

What happens if a list has duplicate items?

Duplicates are collapsed to a single item for comparison purposes. If 'apple' appears three times in List A, it counts as one in the output.

How do I find differences between two Excel lists?

Copy each Excel column and paste into List A and List B. Works the same whether your data came from Excel, Google Sheets, a text file, or was typed in by hand.

What if I need to see how lines changed, not just which lines exist?

Use the Text Diff tool. It shows exactly which characters changed within each line, like a code diff. This compare tool is for set operations on lists. Text Diff is for when the content within individual lines matters.