hdkeygen. This is a very simple and easy-to-use key/wallet generator for Bitcoin (BTC) and Ethereum (ETH). It's implemented in Golang and incorporates the BIP32, BIP39, BIP43, BIP44, BIP49, BIP84, BIP86, BIP173, SLIP44, and EIP55 protocols. This allows for the creation of keys, mnemonic seeds, and Hierarchical Deterministic (HD) addresses.