Compare

Put two documents side by side and find the lines they share, the lines only one has, and duplicates.

Compare answers set questions about two lists: which IDs are in both exports, which emails are only in the new list, which lines repeat.

Start

Open two documents

Open or paste both — for example yesterday's and today's list of customer IDs.

Switch to Compare

Click Compare in the footer's mode switcher, or right-click a tab → Compare with active.

Pick the tabs

Choose the Left and Right tab. Swap exchanges them, Choose files picks again.

Set operations

The toolbar switches what the result shows:

View	Result
Editors	Both documents side by side, editable
Intersection	Lines that appear in both
Union	All distinct lines of both
A−B	Lines only on the left
B−A	Lines only on the right
Duplicates	Lines that occur more than once

Apply to left or Apply to right replaces that document with the result — for example, keep only the new IDs in the right tab with B−A → Apply to right.

Left (A)      Right (B)     A−B     B−A     Intersection
1001          1002          1001    1004    1002
1002          1003                          1003
1003          1004

Tips

Lines are compared as whole lines. To compare one field of JSON records, extract it first — for example ask the AI "reshape to just the id" in each tab.
Line-set operations work on regular tabs. Two large files can be shown side by side, but set operations need regular tabs. See Large files.