DuckDB
A free, tiny program that answers questions about huge CSV and Excel files in a fraction of a second, straight from the file, with no import, no server and no account.
What you can do with it
- Sales by month, store or product from a till export too big for Excel
- Profit and margin by joining a sales file to a cost list
- Turn a 2-million-row file into a small Excel summary for a client
Worth knowingYou ask questions in SQL, so expect some copying, pasting and changing column names at first. The optional browser UI fetches its interface from ui.duckdb.org (needs internet) and shows a MotherDuck sign-in button you can ignore.
The full tutorial
01Install DuckDBFREE02Make a practice file that's too big for ExcelMEMBERS03Ask your first questions, straight from the CSVMEMBERS04Add a cost list to work out profitMEMBERS05Hand the answers back as Excel files, and speed things upMEMBERS06Your SQL starter pack, plus an optional point-and-click windowMEMBERS07Let AI write the SQL for a messy real exportMEMBERS08Turn it into a monthly report a business pays forMEMBERS09Unfair advantages: who has million-row files and pays to understand themMEMBERS
Analyse a million-row spreadsheet in seconds, when Excel gives up · ~75 min · tested 2026-10-09
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