Chess Tactics Pro (Puzzles) – Apps on Google Play

Difficult Chess Puzzles for Advanced Players

hard chess puzzles – Daily Chess Musings

Chess Puzzles - Improve Your Chess by Solving Tactics

Chess Game #8: Checkmate In 1 Move, Black To Play

Problems with the puzzles on - Chess Forums

Understanding soundness and motivations in chess puzzles, problems, and studies

Chess.com - This is the hardest puzzle on Chess.com. Rated 3953. White to move. If you can solve it, AMAZING. 👏 If not, watch NM Sam Copeland explain the complex solution here

Hardest mate in 2!!! - Chess Forums

Chess Puzzles #5: Checkmate In 1 Move, White To Play

Chess Puzzles - Remote Chess Academy