About the Compare Two Lists
Compare Two Lists treats each list as a set of items, one item per line, and tells you how the two overlap. Paste List A and List B and you get five results at once: items only in A, items only in B, items in both, every item from both lists with no repeats, and items in either list but not both. Order does not matter, so it answers questions like “which customers are missing from the second file?” rather than “which line changed?”. It compares whole lines exactly, after the options you choose. It does not look for similar spellings or compare words inside a line.
Updated September 2026
How to use the Compare Two Lists
- 1Paste your first list into List A, one item per line.
- 2Paste the second list into List B.
- 3Choose whether to ignore case, trim spaces, skip empty lines or sort the results.
- 4Copy or download whichever result box you need.
Comparing two lists
Most list comparisons come down to one question: which items belong to one list, the other, or both? Doing it by eye works for ten lines and fails at a hundred. Spreadsheet formulas can do it, but they need setting up every time. Here you paste both lists and read the answer.
Each line is one item. The tool reads the two boxes, removes repeats inside each list, and then checks every item against the other list. Because it uses a lookup rather than comparing every pair, even very long lists finish in a moment on your own device.
What each result means
- Only in A: items that appear in List A but never in List B.
- Only in B: items that appear in List B but never in List A.
- In both: items found in the two lists, in the order they appear in List A.
- All items: List A first, then anything new from List B, with no repeats. This is the union of the two lists.
- In either but not both: only-in-A followed by only-in-B. Useful when you just want everything that does not match.
Case, spaces and empty lines
Lists copied from different places rarely match perfectly. One file has a trailing space, another writes names in capitals. That is why the options are there. Trimming spaces is on by default because stray spaces are the most common reason two identical-looking items are treated as different. Empty lines are ignored by default as well, so blank rows from a spreadsheet do not show up as an item.
Turn on “Ignore upper/lower case” when capitalisation is not meaningful, as with email addresses. Leave it off when it is, for example with case-sensitive codes. If you switch off trimming, a space at the start or end of a line counts as part of the item.
Common uses: emails, SKUs and names
Sorting is optional. When it is on, results use natural order, so “a2” comes before “a10”. When it is off, results keep the order of your lists. Swap A and B if you pasted them the wrong way round.
The tool matches whole lines exactly, after the options you picked. It will not treat “Jon Smith” and “John Smith” as similar, and it does not compare individual words within a line. Everything is worked out in your browser, so a customer or email list is not uploaded anywhere. To sort a list before comparing, use Sort Lines, and use CSV to JSON Converter if the lists come from a spreadsheet.
- Check which subscribers are on your old list but missing from the new one.
- Compare product codes or SKUs from two suppliers to find the shared ones.
- Find names on an attendance sheet who are not on the class roll.
- Compare keyword lists from two tools to see which terms only one of them found.
- Merge two lists without repeats by copying the “All items” box.
Features
- Five results in one go: only A, only B, both, combined and either-but-not-both
- Live item counts for both lists and every result
- Ignore upper and lower case, trim spaces, skip empty lines
- Optional natural sorting, so item 2 comes before item 10
- Swap A and B with one tap
- Copy or download each result on its own
Frequently asked questions
How do I compare two lists?
Paste one list into List A and the other into List B, with one item per line. The five result boxes fill in straight away. Nothing else needs to be pressed, and the counts under each box show how many items each result holds.
How do I find items that are in one list but not the other?
Look at “Only in A” for items missing from List B, and “Only in B” for items missing from List A. If you want both at once, “In either but not both” joins them into a single list.
Can I ignore upper and lower case?
Yes. Tick “Ignore upper/lower case” and “Apple” matches “apple”. The results keep the spelling from the first place the item appeared, so your original capitalisation is not lost. Case folding uses simple lower-casing.
How do I find the common items?
The “In both” box lists every item that appears in both lists. It follows the order of List A. This is the same idea as the intersection of two sets.
Does it remove duplicates?
Every result list shows each item once, even if it was repeated in your input. The line counts in the summary still count each line you pasted, so you can see how many repeats there were. To clean a single list, use Remove Duplicate Lines.
How many items can I compare?
Tens of thousands of lines work comfortably on a normal phone or laptop. Each box accepts up to 2 million characters. Longer text is refused with a message instead of freezing the page.
What is the difference between this and Diff Checker?
Diff Checker compares two texts line by line, in order, and marks what was added or removed. This tool ignores order and compares the lists as sets, which suits email lists, product codes and names.