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Hi there, we have a project where we need a chess engine that plays orthodox Chess that is suitable for web assembly or Javascript, and also has a permissive license. The project involves adapting it to playing our variant requiring three pieces moves to be modified. A rook to a chancellor (so it moves rook+knight). The knight to a wildebeest - also known as a unicorn (so it moves 2+1 and 3+1). And a bishop to an arch-bishop (so it moves bishop+knight).

We want to build bots that can play the game at various rating levels ranging from 100 up to 3000 preferably by configurable parameters.

Anybody know of something that would do the trick?

Garbochess-JS (BDS-3-clause): https://github.com/glinscott/Garbochess-JS
That's the only JS engine with permissive licence that I know, the others are under GPL.

Thanks Ras - this was really helpful.

Garbochess upper limit is ~2000 elo, not 3000

Thanks Yuri - do you know if GarboChess-JS has been tested anywhere?

There is a GarboChess 3.0 in the CCRL 40/15 list, rated 2587/2537 (64bit/32bit). But I guess these are not the JavaScript versions.

Well, FabChess (as Rust) engine can theoretically be made to compile on WASM, and there are current efforts for doing so, although it is not quite there yet, and I am also really unexperienced in that area, but I have one contributor on the project being interested in compilation for WASM . License is also BSD-3, although I can not guarantee I will support your endeavours, you can go ahead and do with Fab what you want.

hgm wrote: ↑Mon Apr 27, 2020 11:10 pmThere is a GarboChess 3.0 in the CCRL 40/15 list, rated 2587/2537 (64bit/32bit). But I guess these are not the JavaScript versions.

This is likely the C++ version. The tomitank Github repo (JS engine under GPL3) says that pure JS is 5 times slower than C. If we assume 60 Elo per doubling, that's 140 Elo, so the JS version of GarboChess should be around 2400.

For online game (is pondering possible??) 40 minute time control seems unapropriate. Top hardware is unexpected.
Maybe fortification with deep-book (Brainfish-style) can help.

Thanks Harm, Fab, Ras and Yuri. All useful comments.