Alternatives to ChessEndings
Play endgames out against an opponent that never gives up. If that's not for you - or you want to try something different - here are apps that overlap on features and use cases.

Chess Tempo
Chess Tempo
The serious puzzle grinder's tool.
Free · from $3.50/mo
4.7Web · iOS · Android

Chess King Learn
Chess King (CHESSQUEEN INC, ex-Convekta)
Huge Convekta course catalog in one app.
Free
4.8Web · iOS · Android

Chess.com
Chess.com, LLC
The default home of online chess.
Free · from $4.17/mo
4.5Web · iOS · Android

Listudy
Arne Vogel
Free open-source spaced repetition for openings.
Free
Web

Lichess
Lichess (charity)
Free, open-source chess. Forever.
Free
4.8Web · iOS · Android

Chess Position Trainer
Stefan Renzewitz
Veteran flash-card repertoire trainer for desktop.
Free
Windows

ChessAtlas
ChessAtlas
Build an opening repertoire that survives spaced repetition.
Free · from $6.99/mo
Web

Chessable
Chessable (Chess.com)
MoveTrainer + spaced repetition for openings and tactics.
Free · from $11.99/mo
4.5Web · iOS · Android