Compare two lists

What people use it for

• Membership and mailing lists: who renewed and who didn't, who's on the newsletter but not the members list.
• Payroll and HR: staff in one system but missing from another.
• Orders and stock: order numbers that were paid but not shipped, or SKUs in your shop but not your spreadsheet.
• Events: who registered but didn't check in, or who RSVP'd twice.
• Teachers: students who haven't handed in an assignment, by comparing the class list with the submissions.

These lists are often confidential, which is why everything happens in your browser. Nothing is uploaded or stored.

Matching messy data

Real lists rarely match exactly. The options above handle the common problems:

• Ignore capitals and extra spaces (on by default): "bob smith " matches "Bob Smith".
• Ignore punctuation: "O'Brien" matches "OBrien" and "Smith, J." matches "Smith J".
• Ignore accents: "José" matches "Jose".
• Ignore word order: "Smith, John" matches "John Smith" (with punctuation ignored too).

When two items match, the "In both" list shows the spelling from list A.

Comparing columns from Excel or Google Sheets

Either copy a column from your spreadsheet and paste it into a box, or export the sheet as CSV (File → Download → CSV in Google Sheets; File → Save As → CSV in Excel) and load it with "Load CSV". If the file has several columns, choose which one to compare.

To do it inside Excel instead, a formula like =COUNTIF(B:B, A2)>0 next to list A shows TRUE for items that are also in column B. The tool above is quicker for one-off checks and for lists that need fuzzy matching.