BIP39 Mnemonic Generator

BIP39 Standard 10 Languages Web Crypto API PBKDF2-SHA512 100% Client-Side

Generate and validate BIP39 mnemonic seed phrases in 10 languages for cryptocurrency wallets. Create secure 12-24 word phrases with cryptographic entropy, verify checksums, and derive 512-bit seeds via PBKDF2-HMAC-SHA512. Supports English, Japanese, Korean, Chinese, Spanish, French, Italian, Portuguese, and Czech wordlists. Uses the native Web Crypto API with zero external dependencies, all processing happens client-side.

Generate Mnemonic
Security: For real wallets, generate offline on an air-gapped device. Never share your mnemonic.
256-bit entropyMaximum
Validate & Derive Seed

Result

No Mnemonic Yet

Generate a new BIP39 mnemonic phrase or validate an existing one.

What is BIP39?

BIP39 (Bitcoin Improvement Proposal 39) is a standard for generating mnemonic phrases that represent cryptographic keys. It provides a human-readable way to backup and restore cryptocurrency wallets using a sequence of common English words.

The process works in four steps: (1) Cryptographically secure random entropy (128-256 bits) is generated. (2) A SHA-256 checksum is appended for integrity verification. (3) The combined bits are split into 11-bit segments, each mapped to one of 2048 words. (4) The mnemonic plus an optional passphrase are fed through PBKDF2-HMAC-SHA512 (2048 iterations) to produce a 512-bit seed for HD wallet derivation.

12 words
128-bit entropy
2128 combinations
18 words
192-bit entropy
2192 combinations
24 words
256-bit entropy
2256 combinations

Security Best Practices

Do

  • Write on paper, store in a safe
  • Use a metal backup plate
  • Generate offline or air-gapped
  • Verify the checksum is valid

Don't

  • Store digitally (photos, cloud, email)
  • Share with anyone
  • Enter on untrusted websites
  • Use for large amounts without hardware wallet

Frequently Asked Questions

BIP39 (Bitcoin Improvement Proposal 39) is a standard for generating mnemonic phrases that encode cryptographic entropy for deterministic wallet key generation. Random entropy is generated, checksummed with SHA-256, split into 11-bit segments mapped to a 2048-word list, then processed through PBKDF2-HMAC-SHA512 with 2048 iterations to derive a 512-bit seed.
This tool processes everything 100% client-side using the Web Crypto API. No data leaves your browser. However, for real wallets with significant funds, we recommend generating mnemonics offline on an air-gapped computer or using a hardware wallet like Ledger or Trezor.
A 12-word mnemonic provides 128 bits of entropy (2^128 combinations), while a 24-word mnemonic provides 256 bits (2^256 combinations). Both are considered secure, but 24 words provides a significantly larger security margin against future advances in computing power.
The passphrase is an optional additional input to the PBKDF2 seed derivation. Each different passphrase produces a completely different wallet, providing plausible deniability. If you lose the passphrase, you lose access to that specific wallet. Only use it if you can securely store it separately from your mnemonic.
No. All cryptographic operations use the native Web Crypto API (crypto.subtle) built into all modern browsers. SHA-256 for checksums and PBKDF2-HMAC-SHA512 for seed derivation are performed natively without any external JavaScript libraries.

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