Are seed phrases generated by this tool safe?

Yes. Random numbers are sourced directly from your browser's CSPRNG (window.crypto.getRandomValues). The tool operates 100% offline with zero server calls. However, for large crypto holdings, hardware wallets (Ledger, Trezor) generated offline are always recommended.

How does the BIP-39 checksum work?

For N bits of initial entropy, SHA-256 is computed and the first N/32 bits of the hash are appended as a checksum. This ensures that typing errors in the mnemonic are immediately caught during recovery.

What is the optional passphrase?

BIP-39 allows an optional user passphrase (often called the 25th word). It is passed into PBKDF2-HMAC-SHA512 to generate a distinct binary seed, functioning as a hidden wallet feature.

BIP-39 Mnemonic Seed Phrase Generator & Verifier

Cryptographically secure BIP-39 mnemonic seed phrase generator based on the official 2048-word English dictionary. Inspect raw entropy, verify SHA-256 checksums, and derive binary root seeds with optional passphrases. 100% private in-browser.

BIP-39 Standard Specifications

Standard Wordlist Mapping

Uses the official Bitcoin BIP-39 English wordlist of 2048 sorted words where the first 4 letters of each word are unique, preventing ambiguity.

Hardware-Level Randomness

Entropy is extracted directly from the operating system's cryptographic random source via window.crypto.getRandomValues, guaranteeing unguessable keys.

PBKDF2 Root Seed Calculation

Derives the standard 512-bit binary seed using PBKDF2 with HMAC-SHA-512 and 2048 iterations as specified in BIP-32 and BIP-44 hierarchical deterministic wallets.