Create Keypair

Private Key

import { Keypair } from "@solana/web3.js";
import * as bs58 from "bs58";

(async () => {
  // 1. create a random
  {
    const keypair = Keypair.generate();
    console.log(`public key: ${keypair.publicKey.toBase58()}`);
    console.log(`private key(raw): ${keypair.secretKey}`);
    console.log(`private key(bs58): ${bs58.encode(keypair.secretKey)}`);
  }

  // 2. from bs58 string
  {
    const keypair = Keypair.fromSecretKey(
      bs58.decode("5MaiiCavjCmn9Hs1o3eznqDEhRwxo7pXiAYez7keQUviUkauRiTMD8DrESdrNjN8zd9mTmVhRvBJeg5vhyvgrAhG")
    );
  }

  // 3. from bytes
  {
    const keypair = Keypair.fromSecretKey(
      Uint8Array.from([
        174, 47, 154, 16, 202, 193, 206, 113, 199, 190, 53, 133, 169, 175, 31, 56, 222, 53, 138, 189, 224, 216, 117,
        173, 10, 149, 53, 45, 73, 251, 237, 246, 15, 185, 186, 82, 177, 240, 148, 69, 241, 227, 167, 80, 141, 89, 240,
        121, 121, 35, 172, 247, 68, 251, 226, 218, 48, 63, 176, 109, 168, 89, 238, 135,
      ])
    );
    console.log(`${keypair.publicKey.toBase58()}`); // 24PNhTaNtomHhoy3fTRaMhAFCRj4uHqhZEEoWrKDbR5p
  }
})();

BIP39

import { Keypair } from "@solana/web3.js";
import * as bip39 from "bip39";

(async () => {
  // 1.
  //   const mnemonic = bip39.generateMnemonic();
  //   console.log(mnemonic);
  // 2.
  const mnemonic = "pill tomorrow foster begin walnut borrow virtual kick shift mutual shoe scatter";

  const seed = bip39.mnemonicToSeedSync(mnemonic, ""); // (mnemonic, password)
  const keypair = Keypair.fromSeed(seed.slice(0, 32));
  console.log(`${keypair.publicKey.toBase58()}`); // 5ZWj7a1f8tWkjBESHKgrLmXshuXxqeY9SYcfbshpAqPG
})();

BIP44

import { Keypair } from "@solana/web3.js";
import { derivePath } from "ed25519-hd-key";
import * as bip39 from "bip39";

(async () => {
  const mnemonic = "neither lonely flavor argue grass remind eye tag avocado spot unusual intact";
  const seed = bip39.mnemonicToSeedSync(mnemonic, ""); // (mnemonic, password)
  for (let i = 0; i < 10; i++) {
    const path = `m/44'/501'/${i}'/0'`;
    const keypair = Keypair.fromSeed(derivePath(path, seed.toString("hex")).key);
    console.log(`${path} => ${keypair.publicKey.toBase58()}`);
  }
  /*
	m/44'/501'/0'/0' => 5vftMkHL72JaJG6ExQfGAsT2uGVHpRR7oTNUPMs68Y2N
	m/44'/501'/1'/0' => GcXbfQ5yY3uxCyBNDPBbR5FjumHf89E7YHXuULfGDBBv
	m/44'/501'/2'/0' => 7QPgyQwNLqnoSwHEuK8wKy2Y3Ani6EHoZRihTuWkwxbc
	m/44'/501'/3'/0' => 5aE8UprEEWtpVskhxo3f8ETco2kVKiZT9SS3D5Lcg8s2
	m/44'/501'/4'/0' => 5n6afo6LZmzH1J4R38ZCaNSwaztLjd48nWwToLQkCHxp
	m/44'/501'/5'/0' => 2Gr1hWnbaqGXMghicSTHncqV7GVLLddNFJDC7YJoso8M
	m/44'/501'/6'/0' => BNMDY3tCyYbayMzBjZm8RW59unpDWcQRfVmWXCJhLb7D
	m/44'/501'/7'/0' => 9CySTpi4iC85gMW6G4BMoYbNBsdyJrfseHoGmViLha63
	m/44'/501'/8'/0' => ApteF7PmUWS8Lzm6tJPkWgrxSFW5LwYGWCUJ2ByAec91
	m/44'/501'/9'/0' => 6frdqXQAgJMyKwmZxkLYbdGjnYTvUceh6LNhkQt2siQp
  */
})();