There is a SAT solver (mine, actually :) ) that's also complied to WASM, and online:<p><a href="https://msoos.github.io/cryptominisat_web/" rel="nofollow">https://msoos.github.io/cryptominisat_web/</a>
I used Emscripten to make a browser-based STP query tool: <a href="http://stp.github.io/live/" rel="nofollow">http://stp.github.io/live/</a> However our API is limited and this has led it to be not so useful and only show valid vs. invalid.