Compare two CSV files and export matched and unmatched rows

CSV-heavy teams reconciling bank, e-commerce, payout, invoice, and accounting exports.

Teams comparing files exported from banks, ERPs, CRMs, payment processors, marketplaces, or spreadsheets.

Excel-heavy users who want less formula maintenance and a clearer review output.

Users open CSV files in Excel, clean headers, choose a key, and run lookups in both directions.

Users usually add helper columns, normalize text and dates, run XLOOKUP or SUMIFS, then filter the remaining exceptions.

The workbook becomes harder to hand off when logic is hidden across copied formulas, pivot tables, or Power Query steps.

CSV comparison gets noisy when date formats, casing, delimiters, or duplicate IDs differ between exports.

Duplicate keys, timing differences, messy descriptions, and gross-vs-net amounts create false exceptions.

Grouped or fuzzy matches are difficult to document when every reviewer sees a different workbook view.

FireLookup compares two CSV files as reconciliation data, not as a developer-style text diff.

FireLookup keeps source files unchanged, lets you select matching rules, and separates matched from unmatched rows.

Exact, fuzzy, one-to-many, and many-to-many matching options help when the files are not simple one-row lookups.