Compare Two Lists Online
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.
First list
Second list
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
- Paste one list into each box, one entry per line.
- Choose what you want to see — shared entries, entries unique to one side, or the merged list.
- Leave case matching off for email addresses and domains; turn it on for identifiers and tokens.
- Copy or download the result.
Example
Input
a b c --- b c d
Output
In both: b, c Only first: a Only second: d
Which setting answers which question
Each option in the Show menu answers a different question about the two lists.
| Show | Answers |
|---|---|
| In both lists | What do the two lists have in common? Also the answer to "which entries are duplicated across both lists". |
| Only in the first list | What is missing from the second list — the entries a migration or an import dropped. |
| Only in the second list | What is new in the second list compared with the first. |
| In one list but not the other | Every difference at once: the list difference in both directions. |
| Both lists combined, duplicates removed | One merged list with each entry exactly once. |
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.
How do I find values missing from one list?
Put the complete list first and the list you suspect is incomplete second, then choose "Only in the first list". The result is every entry the second list is missing. Swap the order, or choose "Only in the second list", to see it the other way round.
How do I find duplicates between two lists?
Choose "In both lists". Every entry that appears in both is a duplicate across the two. To find entries repeated within a single list instead, use the duplicate line remover in its duplicates-only mode.
Can I compare two columns from a spreadsheet or CSV file?
Yes. Copy each column from the spreadsheet and paste one into each box — each cell becomes one line. For a CSV file, pull the column out first with the CSV column extractor, so separators and quoting are handled correctly rather than pasted in.