Compare two CSV files
Load an old and a new version of a CSV and see exactly what changed: rows that were added, rows that disappeared, and the individual cells that were edited.
Loading the tool…How to use it
- Load the original CSV on the left and the new one on the right.
- Pick the key column that identifies a row (such as id or email), or compare line by line.
- Review the summary and the highlighted differences, and download the diff as CSV.
Private by design
The conversion runs as JavaScript in this tab. Your data is not uploaded, logged or stored. There is no account and no file-size paywall.
Why a key column matters
A text diff compares line 5 with line 5. If one row was inserted near the top, every row after it looks changed. Matching on a key column pairs rows by identity instead, so an insert shows as one added row and edits show as the exact cells that differ.
Reading the result
Added rows exist only in the new file, removed rows only in the old one, and changed rows exist in both with at least one different cell, shown as old → new. Columns that were added or dropped are reported separately.
Questions
Is my file uploaded anywhere?
No. The file is read by JavaScript in this tab and never leaves your device. You can load the page, switch off Wi-Fi and it keeps working.
Do the columns need to be in the same order?
No. Columns are matched by header name.
Can I ignore case or whitespace?
Yes, both options are available before comparing.
What if the key column has duplicates?
Duplicated keys are listed as a warning, and only the first occurrence of each key is compared.