In July of 2021 we reported that legal proceedings had begun between the developers of Stockfish, the world’s strongest chess engine, and Chessbase GmbH, developers of various popular chess software. After more than a year of wrangling, that lawsuit has now come to an end with the parties agreeing to a settlement.
Per the agreement, Chessbase concedes they used Stockfish in violation of its license in two of their products, Fat Fritz 2 and Houdini 6. They had previously asserted for years that Houdini was an original creation. They will be prevented from distributing Stockfish in modified or unmodified form for a period of one year, with the exception of re-downloads of already purchased products. This would seem to mean that their big holiday-season product ChessBase 17, which will be released in on November 23rd, will not come packaged with the strongest chess engine available, nor will it contain any of the Stockfish-derived engines that ChessBase has sold in the past.
Furthermore, ChessBase agrees that any future public comparisons they make between their engines and Stockfish will be truthful and use the strongest version of Stockfish. Chessbase had previously published comparisons between Fat Fritz 2, using the newest version of Stockfish, against an older version of Stockfish to try and demonstrate that Fat Fritz was stronger.
Chessbase will also be required to post notices on all web pages connected to Fat Fritz 2 or Houdini 6 making clear that those products come from Stockfish. The YouTube interview where Fat Fritz 2 “head coach” Albert Silver talks about developing Fat Fritz “almost from scratch” now awkwardly contains a notice mentioning the use of Stockfish and its license with the comments section closed. A ChessBase blog promoting that video has now apparently been deleted.
The agreement also includes the necessity to hire a Free Software Compliance Officer to assure that further violations do not occur. Critically, the agreement includes no financial compensation for the Stockfish team, not even legal fees. There are fines for violating the settlement, but they would be paid to the Free Software Foundation Europe and not the Stockfish team.