Secure BIP-39 Generator

Cryptographic Security & BIP-39 Standards

This tool generates a BIP-39 compliant Bitcoin recovery phrase (12, 18, or 24 words) securely within your browser environment. Generating a seed phrase is the most critical step in self-custody; whoever controls these words controls the Bitcoin attached to them. This tool adheres to top-tier cryptographic standards to ensure zero knowledge leakage.

Local Entropy (Randomness): Powered by crypto.getRandomValues(), a cryptographically secure random number generator (CSPRNG) built directly into modern browsers. It pulls high-quality entropy (128, 192, or 256 bits) generated by your device’s hardware noise, completely avoiding weak predictable algorithms like Math.random(). Crucially, no external servers are contacted during this process.

Embedded Wordlist: Uses the official 2048-word BIP-39 English list, stored directly in this file. No network fetches mean no risk of tampering or interception.

Checksum Protection: Adds a checksum (4, 6, or 8 bits, based on word count) from a SHA-256 hash of the entropy. This makes your phrase valid and verifiable by standard wallets.

Offline Security: Save this as an HTML file (right-click, "Save As"), then open it locally with your browser disconnected from the internet. Running it offline eliminates browser risks like extensions or network leaks. For extra safety, use a clean browser with no extensions.

Wallet Compatibility: Your generated seed phrase works with most BIP-39 compliant wallets. Hardware wallets like Ledger (24 words default), Trezor (12 or 24 words), and KeepKey fully support it. Software wallets like Electrum, Blockstream Green, Coinomi, and Trust Wallet also recognize these phrases.

Safety Notes: The seed clears automatically after 5 minutes for your protection. For real funds, always consider a hardware wallet or a dedicated offline tool over a browser-based solution.