Date: 27,28 July
The event will take place in the April offices. April is an association for the defense and promotion of free software.
The offices are relatively close to the Gare Montparnasse railway station.
In addition to trains, Gare Montparnasse railway station has also, in the same building, there is a metro station where you can access the metro lines 4, 6, 12 and 13.
The two main airports near Paris are the Roissy Charles de Gaulle International Airport and the Paris Orly Airport.
To get to the Gare Montparnasse railway station from the Roissy Charles de Gaulle International Airport by public transportation, you can take the RER B metro line up to the Denfert-Rochereau station where you can take the line 6 up to the Gare Montparnasse railway station.
To get to the Gare Montparnasse railway station from the Paris Orly Airport by public transportation, you can take the Orlyval up to the Antony:"https://en.wikipedia.org/wiki/Antony_(Paris_RER)" stop, and from there take the RER B metro line up to the Denfert-Rochereau station where you can take the line 6 up to the Gare Montparnasse railway station.
It also has pages on the Roissy Charles de Gaulle International Airport and the Paris Orly Airport.
Precise schedule:
Saturday: Noon -> Night?
Sunday: 9H or 10H AM -> 14H?