Compare two CSV files

Why a key column

Sorting or re-exporting a file moves rows around, so “row 12 against row 12” compares strangers. Matching by a key — a customer ID, a SKU, an email — pairs each record with itself wherever it sits. Several columns can form the key together.

What you get

• Changed — same key, different values, with each changed cell shown old → new.
• Added — keys only in the updated file. Removed — keys only in the original.
• Columns that exist in only one file are listed, not counted as changes on every row.

Nothing is guessed

• A key that appears twice in a file cannot be paired reliably; those rows are listed as “Not compared”.
• Rows with a blank key are listed the same way.
• Values are compared as exact text unless you choose to ignore spaces or capitalisation, or to compare plain numbers by value (1.50 = 1.5 — thousands separators and currency signs still count).

Downloads

List of changes: one line per changed cell, plus one per added, removed or uncompared row. Full report: every row with its status, its row numbers in A and B, and which columns changed.

Limits

Two files, each a CSV, TSV or delimited text file up to 50 MB or an Excel workbook (.xlsx) up to 10 MB — one sheet of it, chosen by you. Workbook cells are compared as Excel shows them unless you choose the stored values; formulas are not recalculated; older .xls files are not supported.

Privacy

Both files are processed locally in your browser; their contents are not uploaded. The site counts page views and a few anonymous usage events with Umami; they never include file names or contents.