ccxt is good stuff.
[my information may be outdated]
it's _buggy_ so prepare to use it as-is if you want to actually accomplish anything
it uses a quick homebrew transpiler to produce the various apis. efforts to improve the transpiler have mysteriously stalled.
I believe ccxt added support relatively recently for streaming updates, which may provide for lucrative high-frequency trading.
what darknet and p2p exchanges are supported and what features are supported on them, is important information.