BIP39 Mnemonic Generator & Validator
What is a BIP39 Mnemonic?
A BIP39 mnemonic phrase (also called a seed phrase or recovery phrase) is a human-readable representation of the cryptographic entropy that secures your Bitcoin wallet. Instead of memorizing a 256-bit random number, you remember 12 to 24 ordinary English words.
This tool lets you generate new mnemonic phrases or validate existing ones. Everything runs entirely in your browser—no data is ever sent to any server.
How It Works
Generation: The tool uses your browser’s cryptographically secure random number generator to create entropy (randomness). This entropy is then converted into a sequence of words from a standardized 2048-word list. A checksum is appended to detect errors.
Validation: When you enter an existing mnemonic, the tool verifies that each word exists in the BIP39 wordlist and that the checksum is correct. An invalid checksum means at least one word is wrong.
Word Count Options
- 12 words — 128 bits of entropy (standard for most wallets)
- 15 words — 160 bits of entropy
- 18 words — 192 bits of entropy
- 21 words — 224 bits of entropy
- 24 words — 256 bits of entropy (maximum security)
Security Warning
Never enter a real seed phrase into any website. This tool is for educational purposes and generating new phrases only. If you’re validating a phrase you intend to use, do so on an air-gapped device. Anyone who knows your seed phrase can steal your funds.
Learn More
The Complete Guide to BIP39 Mnemonic Seed Phrases — Deep dive into how seed phrases work, the math behind them, security best practices, and common mistakes to avoid.
Crypto Tools Directory — Browse all our Bitcoin and cryptocurrency tools.