Working days vs calendar days?

Working days skip Saturday, Sunday and (optionally) French public holidays. The total span is still shown.

Is a weekend holiday moved to Monday?

No. French law does not generally substitute a Monday.

(01) — TOOLS

Monday–Friday minus French public holidays. Both dates are included, like Excel NETWORKDAYS. A Sunday holiday is not moved to Monday.

Working-day calculator (Monday–Friday), free, in the browser.
Both dates are included, like Excel NETWORKDAYS.
Metropolitan French holidays; optional Alsace-Moselle (Good Friday, 26 December).
A weekend holiday is not moved to Monday.
Nothing is sent to a server.

(02) — METHOD

01 — Working days

A working day is Monday–Friday that is not a public holiday. Not a “business day” in the Saturday-inclusive sense.

02 — Holidays

Eleven metropolitan days, plus Good Friday and 26 December in Alsace-Moselle. Easter-based feasts are computed (computus).

03 — Bounds

Start and end are both counted. If reversed, the tool sorts them.

(03) — FAQ

Working days vs calendar days?: Working days skip Saturday, Sunday and (optionally) French public holidays. The total span is still shown.
Is a weekend holiday moved to Monday?: No. French law does not generally substitute a Monday.
Is anything sent to a server?: No. Dates stay in the tab.