Brain Teasers

Sporcle ›

Massive open-ended quiz library. Every topic, every format. Freemium with a generous free tier. Since 2007.

BrainBashers ›

Long-running aggregator of Sudoku, logic puzzles, and visual brainteasers. Online since 2003.

Lichess Puzzles ›

Same idea as Chess.com puzzles, fully free, open-source, donation-funded. No ads, no premium tier.

Conceptis Puzzles ›

Picture-logic puzzles — Picross, Hashi, Slitherlink. Syndicated to newspapers worldwide since the 1990s.

Daily Puzzle Hunt Cal. ›

Calendar tracking team-based puzzle hunts worldwide. The deeper end of the genre — full weekend events, real prizes.

Janestreet Puzzle ›

A hard math puzzle every month from quant-trading firm Jane Street. Free to attempt; recognition for solvers.

JigsawPuzzles.io ›

Browser-based jigsaw puzzles. Choose any image, any piece count. Free, no signup, multiplayer rooms available.