Jams in Zurich

Planet5

On Thursdays, starting at 19h - free entry. One can come and jam - beginner-friendly.
Website of Planet5 and organizers of the jam (Resonance Jams)
map

Amboss Rampe

Jams on Thursdays, starting at 21:30 - free entry. Usually first half-hour is a concert and then one can register and jam with others - though the level expected seems to be higher than in Planet5.
Website
map

Mehrspur's Jazzraum

On Tuesdays from 20h - first concert, then one can join the jamming session.
Website (see further events under "related")
map

Moods

On Wednesdays, every time new group plays, afterwards may be possible to join the jam.
Website
map