Compare CSV Lists Online

Guide · August 24, 2026

CSV (comma-separated values) is one of the most common formats for exporting tabular data — from Excel, Google Sheets, databases, and SaaS tools. When you have two CSV exports and need to find which rows are new, which are missing, or which overlap, a line-by-line text diff is not the right tool. You need set comparison.

DiffLab's List Compare tool treats each line of your input as a list item and runs five set operations simultaneously. No file upload required.

How to compare two CSV lists

Export your data. In Excel or Google Sheets, copy the column you want to compare (select the cells and press Ctrl+C / Cmd+C).
Paste into List A. Click the left box in the List Compare tool and paste. Each cell becomes one list item, one per line.
Repeat for List B. Paste the second list into the right box.
Read the results. DiffLab shows five panels: Only in A, Only in B, In Both, Union, and Symmetric Difference.

Example: comparing two email lists

Say you have a list of newsletter subscribers from last month (List A) and this month (List B). You want to know who is new and who unsubscribed.

List A (last month)

alice@example.com bob@example.com carol@example.com dave@example.com

List B (this month)

alice@example.com bob@example.com carol@example.com eve@example.com frank@example.com

DiffLab gives you:

Only in A: dave@example.com — Dave unsubscribed.
Only in B: eve@example.com, frank@example.com — Eve and Frank are new subscribers.
In Both: alice@example.com, bob@example.com, carol@example.com — still subscribed.
Union: All five unique emails.
Symmetric Difference: Dave, Eve, Frank — everyone whose subscription status changed.

Drag and drop CSV files

If you have CSV files saved on disk, you can drag and drop them directly onto the List A or List B box. DiffLab parses the file locally using SheetJS (loaded from a CDN) and extracts the first column into the list. The file content is never uploaded — only the parsing library script is loaded from the CDN. See our Privacy Policy for details.

Note: The List Compare tool compares items as plain text. If your CSV has multiple columns, only the first column is extracted. If you need to compare entire rows including multiple fields, use the Text Compare tool with line mode instead, which will show row-level additions and deletions.

Note: Trailing whitespace matters. If your CSV has trailing spaces on some items but not others, the tool will treat them as different. Trim your data in Excel before copying, or use the whitespace normalization option if available.

Compare your CSV lists now.

Open List Compare