In 1944 Paris, where No Exit was first performed in May, the city was under Nazi occupation, and had been since June of 1940. The country's (Vichy) government was under the control of the German military and hand-picked French officials. Curfews determined when people could leave their homes, and Jews were persecuted and ultimately sent to concentration camps. Hundreds of thousands of Parisians left the city because of the occupation; food was scarce, and all media was controlled to disseminate Nazi propaganda.
The Resistance movement coexisted with the occupiers, and its operatives came from all walks of French life to undermine the Germans in many ways, including acts of sabotage, spying, armed conflict, and helping Allied forces. Resistance members reviled the Vichy collaborators as disloyal cowards. It has been said that the occupation presented an existential threat to France itself as a nation and the French identity.
Jean-Paul Sartre was not especially active in the Resistance. His play opened during the occupation, and Nazi officials attended the premiere; it was not censored by German officials. Though some saw the play as a metaphor for the occupation of Paris, Sartre remained quiet on that subject until after the Liberation of Paris in August of 1944. Though he cannot accurately be called a collaborator, it would be an overstatement to describe him as a risk-taking Resistance member who pushed the envelope with the play.