Bip39 Generator

Free online tool. All processing is client-side. No signup needed.

How to Use the Bip39 Generator

1. Enter your input values above
2. Results update automatically
3. Copy or download the output

What is a Bip39 Generator?

A BIP39 Mnemonic Generator creates cryptographically secure recovery phrases (12 or 24 words) used to back up cryptocurrency wallets. BIP39 (Bitcoin Improvement Proposal 39) is the universal standard for wallet seed phrases — the 12-24 word sequence that can restore your entire wallet on any compatible device. This generator uses the Web Crypto API for secure randomness and is fully client-side (the generated phrase never leaves your browser).

How Does It Work?

Choose 12 or 24 words. The generator creates 128 bits (12 words) or 256 bits (24 words) of cryptographically secure entropy, computes a checksum (4 or 8 bits), and maps the bits to words from the BIP39 English word list of 2,048 words. Each word encodes 11 bits of entropy. The last word contains both entropy and checksum.

Formula

12 words = 128 bits entropy + 4-bit checksum = 132 bits → 12×11 bits\n24 words = 256 bits entropy + 8-bit checksum = 264 bits → 24×11 bits\nWord list: 2,048 words (11-bit index per word)\nEntropy source: window.crypto.getRandomValues() (CSPRNG)\n\n⚠️ Never share your mnemonic. Anyone with these words controls your funds.\n⚠️ Generate offline and store securely. Don't type on untrusted keyboards.

Who Uses This Tool?

• Cryptocurrency wallet setup: generating seed phrases for Bitcoin, Ethereum, etc.
• Recovery testing: verifying your backup phrase works before needing it
• Education: understanding how wallet backup and recovery works
• Hardware wallet initialization (always use the device's own generator for real funds)

Pro Tips

• Never generate seed phrases on a website for real funds — always use a hardware wallet (Ledger, Trezor) or audited wallet app
• Store your recovery phrase: (1) write on paper (never digital), (2) store in fireproof safe, (3) consider steel backup (stamped metal) for flood/fire resistance
• The 24-word phrase provides 256 bits of security — more than the 128-bit security of Bitcoin's secp256k1 curve. 12 words (128 bits) is sufficient for most users

Frequently Asked Questions about Bip39 Generator

Is it safe to use this generator for real wallets?

This tool is for educational/testing purposes. For real cryptocurrency wallets, always use a hardware wallet or audited wallet software that generates seeds in an isolated environment.

Why 2,048 words in the BIP39 list?

2,048 = 2^11 — each word encodes exactly 11 bits. The words were chosen to be unambiguous (no similar words like 'cat' and 'cats'), short, and recognizable across languages.

Free online Bip39 Generator — no signup, 100% client-side processing. All data stays in your browser.