The metro's no-cover institutions are a real thing. The 331 Club anchors it; Sociable Cider, Indeed taprooms, public-park concerts fill the rest.
The 331 Club runs live music almost every night with no cover — the cash-tip-the-band model is how the room stays sustainable, so bring small bills. Aster Cafe charges modestly. The summer brings free music at Peavey Plaza, Mears Park (Lowertown), and various brewery taprooms (Indeed and Bauhaus run regular free nights). For ticketed shows under $15, the 7th St Entry is the consistent answer.
Summer free-music: check Peavey Plaza in front of Orchestra Hall on a weeknight, or Mears Park in Lowertown for Wednesday-night programming.
A small corner bar at 13th and University running live music almost every night of the year. No cover. Two or three sets a night, often a 7 PM act and a 9:30 PM act, sometimes a third late. Strong local rotation, Harold's House Party on KFAI broadcasts from the room some Wednesdays. The kind of place you walk into in flannel and stay until last call. Northeast institution.
A small Mississippi-riverfront cafe with a tiny stage that punches well above its size. Acoustic shows, jazz brunches, and a patio that is one of the best in the city for a quiet drink and a song or two on a summer evening.
The room. Prince filmed Purple Rain here. The black stars on the outside wall track every act that has played the venue. The Mainroom is one of the best mid-sized rock clubs in the country, and the 7th St Entry next door is the small room where bands try out the city before they grow into the big stage. If you only see one show in Minneapolis, see it here.