BIP39 Mnemonic Generator
Generate cryptographically secure BIP39 mnemonic phrases (12 or 24 words) and validate existing ones. Runs 100% in your browser — your seed phrase never leaves your device.
Important security warnings
- Never use a mnemonic generated on ANY website for real funds. This tool is for education and testing only.
- Never share your mnemonic with anyone, ever. It gives complete control of your wallet.
- Never save your mnemonic to localStorage, cloud storage, email, or screenshots.
- Never use this on a compromised or public computer.
- For real wallets, generate offline using hardware wallets (Ledger, Trezor) or trusted offline tools.
Generate and validate BIP39 mnemonic seed phrases entirely in your browser with SolveBar's BIP39 Generator. Uses the browser's cryptographic random number generator for secure phrase generation. For educational and testing purposes only — never use browser-generated phrases for real funds.
What is BIP39?
BIP39 defines a standard for encoding cryptographic seeds as human-readable word sequences. A 12-word phrase encodes 128 bits of entropy, while 24 words encodes 256 bits. The words are chosen from a standardized list of 2048 English words.
How BIP39 derives wallet keys
The mnemonic phrase is converted to a seed using PBKDF2 with 2048 iterations of HMAC-SHA512. This seed is then used with BIP32/BIP44 to derive a hierarchical tree of key pairs. The same 12-24 words will always recreate the same wallet across any compatible wallet software.
Security warnings for real use
Never generate real wallet mnemonics in a browser. Use a hardware wallet (Ledger, Trezor) or an air-gapped device for real wallets. Never enter your real seed phrase into any website. Never store your seed phrase digitally — write it on paper and store it securely offline.
Frequently Asked Questions
Is this safe to use for a real wallet?
No, and this applies to every browser-based generator, not just this one. Although generation happens locally using the browser's cryptographic random number generator and nothing is transmitted, a browser environment cannot guarantee isolation from extensions, malware, or clipboard snooping. For real funds, generate your seed phrase on a hardware wallet (Ledger, Trezor) or a permanently air-gapped device. Use this tool for learning how BIP39 works, testing wallet software, and generating disposable development phrases.
Can I validate an existing mnemonic without entering it online?
Your real seed phrase should never be typed into any internet-connected website, including this one. To validate a real mnemonic, use an offline, open-source tool on an air-gapped machine, or your hardware wallet's own recovery-check feature. The validator on this page is designed for test phrases — checking that development mnemonics have valid BIP39 checksums and word-list membership before you use them in test suites.
What is the difference between 12 and 24 word phrases?
A 12-word phrase encodes 128 bits of entropy; a 24-word phrase encodes 256 bits. Both are far beyond brute-force reach — 128 bits already exceeds what any conceivable hardware could search. Hardware wallets often default to 24 words for defense-in-depth margin, while many software wallets use 12 for easier backup. The practical risk to either is never brute force: it is physical discovery, phishing, or digital storage of the written phrase.
How does a BIP39 phrase become actual wallet keys?
The mnemonic is run through PBKDF2 with 2048 iterations of HMAC-SHA512 (optionally salted with a passphrase) to produce a 512-bit seed. That seed feeds BIP32 hierarchical deterministic derivation, which generates a tree of private keys along standardized BIP44 paths — one branch per coin, account, and address index. This is why the same 12 or 24 words restore the same addresses in any compatible wallet.