Copilot for Excel that looks it up instead of making it up.

Ask your workbook in plain English. Prereasoner types your columns, resolves your values, and computes the answer as a query you can open. It will not silently return a wrong total.

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Compare to Copilot

Why us

The answer comes with the query that produced it

The number, and the query that made it

Every answer arrives with the exact query it ran on your sheet. Open the query to verify the filter, calculation and source rows.

It tells you when your sheet falls short

Ask about a region your data does not cover and it says so. A visible gap is cheaper than a plausible figure that fails your audit.

Never writes into your data

Your source sheet is read, never altered. Derived columns and lookups appear separately, so pasting in new data never overwrites a hidden helper column.

The values that need a source

Rare, private, historical and dated facts are looked up from authoritative, dated sources, and the source is shown with the answer.

Head to head

Prereasoner vs Microsoft 365 Copilot

Copilot is good on common, public data. The difference shows up on the numbers you can't afford to have guessed.

On your spreadsheet	Microsoft 365 Copilot	Excel Copilot by Prereasoner
Common calculation on clean data	Good	Good
Shows the formula / query	Usually	Always
Can silently return a wrong number	Yes	No
Ambiguous entity (Paris, FR vs TX)	Guesses one	Resolves or asks
Historical or dated value	Uses today's or a guessed value	Dated lookup with source
Writes helper columns into your data	Yes, with overwrite risk	No, kept separate
Runs on premises	Cloud only	Self-hostable

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Copilot for Excel that looks it up instead of making it up

Upload an .xlsx and get the result with its query and source rows. Start with 50 questions a month.