BIP39 Mnemonic Tools
BIP39 encodes random entropy as a 12–24 word mnemonic and derives a wallet seed from it. Generate, validate and convert test data here — in your browser, with nothing sent anywhere.
Working with a real recovery phrase? Use the offline version: download it, verify its SHA-256, and open it with networking turned off.
Tools
Generator
12, 15, 18, 21 or 24 words from secure browser randomness, with entropy and checksum shown.
Validator
Finds invalid word counts, misspelled words (with suggestions) and checksum mismatches.
Converter
Entropy → mnemonic, mnemonic → entropy, and mnemonic + passphrase → seed.
Checksum
Step through SHA-256, checksum bits and 11-bit groups with official test vectors.
Word List
Search 2048 words by word or number; download TXT, JSON or CSV with hashes.
Passphrase demo
See how one mnemonic produces different seeds with different passphrases.
From entropy to seed
128–256 random bits
→ 11-bit groups
12–24 words you write down
2048 rounds + passphrase
512 bits, the input to wallet key derivation
Offline and open source
Check it instead of trusting it
- Version
- 0.1.0 (211d6ed)
- License
- MIT
- Source code
- github.com/gonglian8-stack/bip39-ai
- Network requests while computing
- None — blocked by Content Security Policy
- Test vectors
- All 24 official English vectors pass, plus cross-checks with python-mnemonic
- Independent audit
- Not yet available
Offline tool
One HTML file with the generator, validator, converter, checksum and word list. No network access, no external files.
Core concepts
- Entropy
- 128–256 random bits. Everything else is derived from it.
- Mnemonic
- The entropy plus a checksum, written as 12–24 words from a 2048-word list.
- Checksum
- A few bits of SHA-256 in the last word that catch typos. How it works.
- Passphrase
- Optional extra text; changes the seed completely. Demo.
- Seed
- 512 bits derived from words + passphrase, used by BIP32 to create keys.
Frequently asked questions
Is BIP39.ai a wallet?
No. It has no accounts, never connects to a blockchain, and does not show private keys, addresses or balances. It is a set of tools and explanations for the BIP39 standard.
Does anything I type leave my device?
No. All tools run in your browser and the site’s security policy blocks the page from making network connections. You can confirm it in your browser’s developer tools. See the security model.
When should I use the offline version?
Whenever real recovery phrases or passphrases are involved. Download the file, check its SHA-256, disconnect from the network, then open it. Get the offline tool.
Can this site recover a wallet or find missing words?
No. It does not recover wallets, brute-force missing words or guess passphrases.