Here you can play against the chessmail online chess computer. The program runs with a Stockfish engine, one of the currently strongest chess computer engines.
Level 1 is relatively easy and allows beginners to win a game. Level 2 is for somewhat experienced players and from level 3 the chess computer becomes a serious opponent, also for club players. The displayed score is always the score from the point of view of the white figures. A value above 0 means a good position.
The chessboard, the notation display and the buttons with which you operate this chess computer belong to a program called chess-console. chess-console is an open source project that you can also install on your website under consideration of the license terms.