THE DATA DESK · 01

Find the record.
Then find the change.

When rows move, line-by-line comparisons get noisy. Match two CSV exports by a stable, unique ID to see which records changed.

Compare two small exports

Download before.csv and after.csv. Choose Compare two files, load A and B, select id as the match column, then choose Find differences.

File A

id,name,city
001,Rae,Boston
002,Jin,Seattle
003,Ana,Chicago

File B

id,name,city
001,Rae,Boston
002,Jin,Portland
004,Leo,Denver

Expected: 3 differences. ID 001 is unchanged.

Key	Status	Meaning
002	Changed	city: Seattle → Portland
003	Only in A	Ana is missing from the newer export
004	Only in B	Leo appears in the newer export

Reordering either file does not change the match. A duplicate or empty ID stops the comparison because the tool cannot select the correct record reliably.

Open CSV cleaner & compare ↗

Clean the file before matching

Download messy.csv. In “Clean a file”, leave “Trim extra spaces” and “Remove empty rows” enabled, turn on “Remove duplicates”, and match by id.

Expected: 3 output rows, 1 duplicate removed, and 1 blank row removed.

Deduplication keeps the first matching row. Review conflicting duplicates before using a key: two records with the same ID and different names will not be merged. The header row is retained; trimming applies to data cells.

What this workbench compares

Files are UTF-8 CSV or TSV, up to 15 MB each. Commas, tabs, and semicolons are detected; exported CSV uses commas.
Quoted commas, quoted line breaks, escaped double quotes, and a UTF-8 BOM are supported.
Each file needs a header with distinct, nonempty column names and consistent row widths.
Only columns with exactly matching names are compared. Unmatched columns are listed separately; they are not silently compared by position.
Match keys are trimmed. Other cells compare as text, so 1 differs from 1.0 and trailing spaces can matter.
The preview shows 50 rows. The download includes every result row. This is a CSV tool, not an Excel workbook or formula engine.

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Reference

RFC 4180 — common CSV format. The examples describe this tool’s behavior; verify the requirements of your own system before using an output.

Find the record.Then find the change.