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List Comparison

The list comparison tool treats two lists as sets and shows what they have in common, what is only in the first, what is only in the second, or the combined list with duplicates removed. Order does not matter and repeats within a list are collapsed, which is what makes it different from a line-by-line diff.

Options
First list 0 characters
Second list 0 characters
Result

Your result will appear here.

Not sure where to start? Use Load example.

Results update automatically and are calculated on your device. Nothing you type is sent to a server.

Runs in your browser. Processing happens entirely in your browser. Nothing you enter is sent to Delimiter.live.

How to use the List Comparison

  1. Paste one list into each box, one entry per line.
  2. Choose what you want to see — shared entries, entries unique to one side, or the merged list.
  3. Leave case matching off for email addresses and domains; turn it on for identifiers and tokens.
  4. Copy or download the result.

Example

Input
a
b
c
---
b
c
d
Output
In both: b, c
Only first: a
Only second: d

Common use cases

  • Finding which subscribers appear on both an old and a new mailing list.
  • Working out which records a migration missed by comparing two exports.
  • Checking which items were added or removed between two inventory lists.
  • Merging two lists of tags or keywords without producing duplicates.

Limitations and things to watch for

  • Entries are compared as whole lines. Two lines meaning the same thing but written differently — a name with and without a middle initial, say — are treated as different entries.
  • Repeats within a single list are collapsed before comparing, so this answers "is it present?" rather than "how many times?". Use the duplicate line remover in its duplicates-only mode for counts.
  • Blank lines are ignored entirely rather than treated as an entry.

Frequently asked questions

How is this different from the text difference checker?
The difference checker asks what edits turn one text into the other, so order matters and it reports moved lines as a change. This treats the lists as sets: order is irrelevant, and it answers what they share and what only one of them has.
Does the order of my lists matter?
No. Entries are matched by value, not position, so two lists containing the same entries in a different order are found to be identical.
What happens to duplicates within one list?
They are collapsed to a single entry before comparing, and the first spelling encountered is the one shown. The summary line reports how many unique entries each list held.
Should I turn case matching on?
Leave it off for email addresses, domains and URLs, where case carries no meaning in practice. Turn it on for identifiers, API keys and anything where Admin and admin are genuinely different values.
Are my lists uploaded?
No. Both lists are compared in your browser, which matters because the lists people compare are usually customer records or email addresses.

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