List Comparison Tool
Compare two lists to find items in both, in only one, or in neither, with case and whitespace options, duplicate counting and set operations on the results.
Last reviewed by the Radiatus Cloud team
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Set comparison answers a different question from diffing
A diff tells you how one file changed into another, and it cares about order and position. Set comparison ignores both and answers a different question: which entries appear in both lists, which are unique to each, and how many there are. For comparing two exports of email addresses, two lists of SKUs, two sets of user IDs or the contents of two directories, the set answer is the one you want and the diff is unreadable noise.
Normalisation decides the answer
Whether "Alice@Example.com" and "alice@example.com" are the same entry depends entirely on what the list represents. Email local parts are technically case sensitive and almost never treated that way in practice; domains are not case sensitive at all. Product codes usually are. Trailing whitespace from a spreadsheet export is invisible and makes two identical looking entries compare as different, which is the most common cause of a comparison returning nothing in common when it obviously should.
Duplicates carry information
A plain set comparison collapses duplicates and therefore hides them. Knowing that an identifier appears three times in one list and once in the other is frequently the point of the comparison, particularly when reconciling records that should be unique. Counts are reported separately here so the set answer and the multiplicity answer are both available.
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Frequently Asked Questions
How is this different from a diff tool?
A diff cares about order and position and shows how one text became another. Set comparison ignores order entirely and answers which entries the two lists share. For exports of identifiers, email addresses or filenames, the set answer is the useful one.
Why does my comparison find nothing in common?
Almost always trailing whitespace or a case difference. Whitespace from a spreadsheet export is invisible and makes two identical looking entries compare as different. Enable trimming and case insensitive matching to check.
Should the comparison be case sensitive?
It depends on what the list represents. Domain names are not case sensitive, email local parts technically are but are rarely treated that way, and product codes and identifiers usually are. Choosing wrongly changes the answer rather than the presentation.
What do the set operations mean?
Intersection is items in both lists. A only and B only are the items unique to each, also called the differences. Union is everything from both with duplicates collapsed, and the symmetric difference is everything that appears in exactly one of the two.
Why report duplicate counts?
Because a set comparison collapses duplicates and hides them. When reconciling records that should be unique, knowing that an identifier appears three times in one list and once in the other is often the whole point of the exercise.
Privacy & Security
Everything runs in your browser; nothing is uploaded.
How to Use
Paste two lists to see which items they share and which are unique to each.
Disclaimer: This tool is provided "as is" without warranty of any kind. Results are for educational and utility purposes.
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