Private CSV lookup join workspace

Add columns from a supplier list, price sheet or customer lookup to an existing CSV without overwriting original values. See what matched, what did not, and download both the joined CSV and an unmatched-key review file.

First CSV — rows you want to keep

This file stays the primary table. Rows appear in the same order in the output.

Choose first CSV file (up to 2 MB)

Lookup CSV — columns to add

The lookup key must be unique and nonblank; matching values supply new columns.

Choose lookup CSV file (up to 2 MB)

First CSV matching keyLookup CSV matching keyWhich rows should be in the output?Match keys case-sensitively (recommended for SKU / ID)

Join summary

Joined CSV preview

Rows with no matching lookup key

Never import the joined result into a live store without checking it against the source. Duplicate lookup keys, blank lookup keys and mismatched CSV field counts are rejected. This tool does not contact Shopify, Google Sheets or another account.