The French language is only one of the langues d’oil, a group of languages that developed out of Old French around ~1000. They’ve all been separated from Old French for about 1,000 years. It’s uncertain how many of these are still alive. It’s also unknown how many are still full languages and how many have simply turned into dialects of regional French. Mutual intelligibility is also not known with most of these languages and few if any studies have been undertaken. Another problem is that the languages themselves range from forms of regional French to full-blown separate languages.
The French language itself is a langue d’oil called Francien that was chosen as the de facto French language several hundred years ago. However, as recently as 100 years ago, 80% of conscripts in the French Army in WW1 could not speak French!
Percheron, spoken very close to Paris. Said to be extinct but there are still some speakers. Together with Sarthois in Manceau.
Berrichon, spoken in Berry. Said to be extinct but still has speakers.
Tourangeou, spoken in Tours. Said to be extinct, but it is still spoken in the rural areas.
Orleanais, said to be extinct but still spoken in the rural areas.
Manceau or Mainot, spoken in Mans. Said to be a French dialect, but is really a language. Said to be extinct but still spoken. Includes Percheron and Sarthois.
Sarthois, spoken in Sarthe, probably a separate language. Together with Percheron in Manceau.
Mayennais, spoken in Mayenne, probably a separate language.
Gallo, still spoken in Brittany, 300,000 speakers. Lot of Breton words. Gallo was formed from Manceau, Sarthois, Mayennais, and Percheron.
Angevin, spoken in Anjou, together with Gallo but a separate language. Said to be nearly extinct but still spoken.
Poitevin, spoken in Poitiers, separate language. There are still native monolinguals in their 60’s who cannot even speak French!
Saintangenais, spoken in Western France, separate language. Still fairly widely spoken. This is together with Poitevin.
Norman or Normand, different types, separate language, still spoken. Cotentinais still has native speakers in their 40’s, farm workers.
Gernesiais Norman, spoken on Guernsey. Probably two different languages.
Jerriais, spoken on Jersey, separate language from Gernesiais.
Sercquiais, spoken on Sark Island, only 15 speakers left, separate language.
There are different Norman forms spoken on the mainland in Normandy. Cauchois, Cotentin, etc.
Picard, spoken in Picardy, still widely spoken in different forms that all seem to be dialects of one language. A separate language, still fairly widely spoken, especially by coal miners.
Champenois spoken in Champagne, still spoken but going extinct, separate language. Ardennois is a dialect spoken in the Ardennes, still spoken.
Lorrain spoken in the Loire, still spoken in different forms but going extinct.
Bourguignon, separate language, still spoken in Burgundy. Fairly widely spoken.
Bourbonnais, probably a separate language, spoken in Burgundy. Close to Berrichon.
Franche-Comte, still spoken in Franche-Comte mostly by old people.