Compare two columns, find differences
Runs locally · Nothing uploaded
An online two-column comparison tool for finding the differences between two lists. Paste each list into the left and right panels and it instantly computes left-only items (A-B), right-only items (B-A), matches on both sides, the deduplicated union, the complement, and changed values, showing them in six categorized result cards. It is handy for reconciling two columns in a spreadsheet, diffing config entries between environments, checking which fields an API added or removed, and cleaning up duplicates. Everything runs locally in your browser and no data is uploaded to a server.
It compares any two lists of line-based text and works out which items appear only on the left, only on the right, on both sides, plus changed values for Key=Value and CSV data. It also reports the intersection, union and complement — useful for reconciling lists, config entries, field inventories and spreadsheet columns.
Yes. Copy each column from Excel and paste it into the left and right inputs (one item per line). For CSV data you can also upload or drag the file in and use CSV mode.
Difference A-B is what appears only on the left; B-A is what appears only on the right. The intersection is what both sides share, the union is everything combined and deduplicated, and the complement is the right side relative to the left (another view of B-A).
No. All comparisons run locally in your browser. Nothing is uploaded or stored on a server, and the data disappears when you close the page, so it is safe for internal lists and configuration data.
Deduplication of results is enabled by default, so repeated lines appear once. Uncheck it if you want duplicates counted, and enable ignore empty lines to keep blank lines from showing up as differences.
Yes. The Excel export has one worksheet per category: Summary, Left Only, Right Only, Changed, Intersection, Union and Complement. CSV is a single-table format, so all categories go into one file distinguished by the Type column — use Excel when you need separate sheets.