CSV Diff

Paste or upload two CSVs, choose the same key column on both (for example id), and see rows that were added, removed, or changed. Matching uses the first row when duplicate keys exist; duplicates are called out in a warning. For raw text, use text diff.

Delimiter (both files)

Delimiter

First row is header

CSV A (before) Clear

Drop file A · shared CSV limits

CSV B (after) Clear

Drop file B · shared CSV limits

Key columns

Primary key

Secondary key (optional)

Headers must appear in both files. Composite key = primary + secondary.

Hide unchanged rows in the table

Results

Added in B Removed from A Changed Unchanged

Key	Status	Details

Compared only in your browser. No uploads.

HOW TO

How to compare CSV files

Align two exports on a stable key, run the comparison, then scan the table or download a text report.

Paste both CSVs

Use the same delimiter for both, or choose Auto. Confirm the first row is your header.

Pick the key

Select the primary key column (and optional secondary) that exists in both files.

Review adds, removes, changes

Read per-row details or copy/download the full report.

FAQ

Frequently asked questions

What if the same key appears on multiple rows?

The tool warns you and lists duplicate keys. Comparison uses the first matching row per file for that key; fix duplicates in the source CSVs if you need every row differenced.

Do column names have to match?

Key columns must share the same header text in both files (after trim). Other columns are compared by matching header name; columns only in one file are noted in change details.

Is my data uploaded?

No. Parsing and diff run entirely in your browser.