DiffKit / Compare two lists
Compare two lists
Paste two lists, one item per line or separated by commas. You get what’s only in list A, what’s only in list B and what they share, ready to copy.
What the four results mean
Think of the two lists as overlapping circles. Only in A is the difference A − B: items to remove, customers who churned, files missing from the new build. Only in B is B − A: new sign-ups, added dependencies. In both is the intersection, and All unique is the union with duplicates collapsed.
The bar above the results is drawn to scale: magenta for items only in A, yellow for the overlap and cyan for items only in B. It works like a quick Venn diagram, so you can see at a glance whether two exports are nearly the same or barely overlap.
Comparing whole files line by line, with order preserved, is a different job. Use the diff checker for that, or the CSV compare when rows have several columns.
Questions people ask
How do I compare two lists in Excel instead?
A common formula is =COUNTIF(B:B, A2)=0 next to list A, which returns TRUE for items missing from B. This page gives the same answer for both directions at once, plus the overlap, without writing formulas.
Does it treat “Apple” and “apple” as the same?
Yes while “Ignore case” is ticked, which is the default. Untick it for exact matching, which matters for things like case-sensitive IDs or file names on Linux.
Can I paste comma-separated values?
Yes. With “Auto”, text that contains line breaks is split per line and single-line text is split on commas, semicolons or tabs. You can force either mode.
What happens to duplicates?
With “Remove duplicates” on, each value appears once in the results. The counters above the results still tell you how many duplicates each list contained.
Is there a limit on list length?
Comparisons use hash sets, so tens of thousands of items compare in a fraction of a second on a normal laptop. Nothing is uploaded.