BIP39 Mnemonic Generator
Generate 12–24-word English BIP39 mnemonics for testing and learning.
// 100% CLIENT-SIDE — your seed phrase is generated locally and never sent over the network
// SECURITY WARNING
Generated locally for development, learning, or testnet use only. For real wallets that secure non-trivial value, ALWAYS use a hardware wallet or trusted offline tool. Never enter a real seed phrase into any web page.
Crypto-Grade Entropy
Random bytes come from window.crypto.getRandomValues(), the same CSPRNG used by Web Crypto, TLS, and modern wallets.
100% Client-Side
The full 2048-word English wordlist is bundled inline. No network calls during generation — you can even disconnect your machine and the tool still works.
12 to 24 Words
Choose 12, 15, 18, 21 or 24 words. This page generates the mnemonic only; it does not derive a binary seed.
// ABOUT BIP39
How Generation Works:
Random entropy from crypto.getRandomValues() is combined with ENT/32 SHA-256 checksum bits. Each 11-bit group selects a word from the standard 2048-word English list.
Example:
12 words = 128 entropy bits + 4 checksum bits = 132 bits = 12 × 11-bit indices into the wordlist.
Standards:
- >BIP-0039: Mnemonic code for generating deterministic keys
- >Official 2048-word English wordlist (11 bits per word)
- >Mnemonic strength: 128, 160, 192, 224, or 256 entropy bits
- >Web Crypto API: crypto.getRandomValues + SubtleCrypto.digest(SHA-256)
Common Use Cases:
- >Bootstrap a new HD wallet (BIP32/BIP44)
- >Test wallet recovery flows in a dev environment
- >Teach key-management concepts to new crypto users
- >Generate disposable seeds for unit tests
- >Audit how mnemonics map to entropy + checksum
>> frequently asked questions
Why are the generated words in English?
The generator uses the standard 2048-word English BIP39 list. Changing the page language does not change that list.
Does this page derive a binary seed?
No. It generates the mnemonic only. Seed derivation and an optional BIP39 passphrase are separate steps performed by a wallet tool.
Which word counts are supported?
12, 15, 18, 21 and 24 words, corresponding to 128, 160, 192, 224 and 256 bits of entropy.
Can I use it for a wallet with real funds?
Use this page for learning and testing. Generate real recovery phrases with a trusted wallet device or offline tool.