List Comparison Generator
Comparing two lists by eye is exactly the sort of thing people get wrong at the twentieth entry. This splits them into three parts — only in the first, only in the second, and in both — ignoring case and stray spaces, and then checks that the three parts account for every distinct entry exactly once, which is the failure worth guarding against.
What this generator does
Trims and case-folds both lists, collapses repeats within each, and splits the combined entries into the three parts. The parts are then checked to partition the union with no overlap and nothing missing.
How to use this tool
- Paste one list into each box, one entry per line.
- Read the three columns.
- Note that repeats within a list are collapsed first.
- Copy whichever part you need.
Understanding the controls
- First list
- One entry per line. Case and extra spaces are ignored, so \u201cAda Lovelace\u201d and \u201cada lovelace\u201d match.
- Second list
- The list to compare against. Order does not matter; the results are sorted alphabetically.
Common use cases
- Finding who is on one guest list but not the other
- Comparing an invite list against a list of replies
- Checking which items are missing from a stocktake
- Spotting entries added or removed between two versions of a list
- Finding the overlap between two sets of names
How this generator works
Both lists are normalised — trimmed, lower-cased and with runs of spaces collapsed — and turned into sets, which removes repeats within a list. The three parts follow directly from set membership. Before display the parts are checked to hold exactly the distinct entries across both lists, with no entry in two parts and none missing, and each part is re-tested against its own definition.
Randomness and fairness
Nothing here is random. Two lists give exactly one comparison.
For how randomness is produced across the whole site, see how Generate Random works.
Limitations and good to know
- Comparison is exact after normalising, so \u201cStephen\u201d and \u201cStephan\u201d are different entries — the near-duplicate detector is the tool for near matches.
- Repeats within a list are collapsed, so this compares which entries appear rather than how many times.
- Entries are compared as whole lines, so a list with extra columns needs splitting first.
- Sorting is alphabetical rather than in the original order.
Privacy and your data
Both lists stay in your browser. Nothing is uploaded, stored, or included in analytics — only how many entries were compared.
Related generators
- Near-Duplicate Name DetectorFinds entries in a list that are the same, nearly the same, or merely sound the same — with every pair checked in both directions.
- Text Diff GeneratorCompares two texts line by line and shows the smallest set of changes, checked by applying them back to the original.
- Random Name PickerPaste a list of names and instantly pick one at random, fairly and without repeats if you choose.
- Quota Sampling GeneratorSplits a sample across groups in proportion to their size, with the quotas adding up to exactly the sample size and nobody picked twice.