BIP39 Mnemonic Generator

1. Select word count — Choose 12, 18, or 24 words. More words = higher security.
2. Generate — Click the Generate button. A new cryptographically secure mnemonic phrase is created using your browser's Crypto API.
3. Copy and save — Copy the phrase and store it securely offline. The phrase is your wallet's master seed.
4. Verify — Always verify your backup by restoring the phrase in your wallet before sending funds.

All generation is performed 100% client-side in your browser using crypto.getRandomValues() for cryptographically secure entropy. No data is sent to any server.

BIP39 (Bitcoin Improvement Proposal 39) defines the standard for generating mnemonic seed phrases used in hierarchical deterministic (HD) wallets. A BIP39 mnemonic is a sequence of words chosen from a fixed wordlist of 2048 words that encodes a random entropy value used to derive all wallet keys.

The generation process works as follows: random entropy (128, 192, or 256 bits) is generated, a checksum derived from SHA-256 is appended, and the combined bit string is split into 11-bit segments. Each 11-bit value (0-2047) maps to a word in the BIP39 English wordlist, producing the mnemonic phrase.

The mnemonic can optionally be combined with a passphrase (BIP39 passphrase) to generate the wallet seed, adding an extra layer of security. The standard is supported by virtually all cryptocurrency wallets, including Bitcoin Core, Ledger, Trezor, MetaMask, Trust Wallet, and many others.