bs58
Base 58 encoding / decoding
bs58check
A straightforward implementation of base58-check encoding
eckey
Handle private key and public keys associated with elliptic curve cryptography. Used with crypto currencies such as Bitcoin, Litecoin, Dogecoin, etc. Works in both Node.js and the browser.
ccxt
A JavaScript / TypeScript / Python / C# / PHP cryptocurrency trading library with support for 100+ exchanges