BIP39 Mnemonic Generator

Generate cryptographically secure BIP39 seed phrases for educational and development use.

Last reviewed: April 2026
Reviewed by , software engineer · last updated April 2026

New to this tool? Click here for instructions

For educational purposes only. Never use an internet-connected tool to generate mnemonics for real funds. Use a hardware wallet (Trezor, Ledger) or an air-gapped device for actual cryptocurrency recovery phrases.
Generated Phrase
Click "Generate Phrase" to create a mnemonic
Plain text (space-separated)
Select a word count and click Generate Phrase.

Quick Answer

A BIP39 mnemonic is the human-readable seed phrase — typically 12 or 24 words — that a crypto wallet uses to derive its keys. This tool generates a valid BIP39 phrase from the standard 2048-word list with a correct checksum. Generate a phrase above. It runs entirely in your browser, but never use a web-generated phrase to secure real funds.

How to Use the BIP39 Mnemonic Generator

To use the BIP39 Mnemonic Generator, follow these steps:

1. Select the desired word count (12, 15, 18, 21, or 24 words).

2. Click 'Generate Phrase' to create a mnemonic.

3. Review the entropy details to understand the security level.

4. Copy or download the generated mnemonic for offline storage.

When to Use the Tool in Real Workflows

Use the BIP39 Mnemonic Generator when you need to create a secure seed phrase for a cryptocurrency wallet or other cryptographic application. It is particularly useful for educational purposes and development to understand how mnemonic phrases are generated and verified.

How It Works

The BIP39 Mnemonic Generator works by following these steps:

1. Generate cryptographically secure random entropy.

2. Compute the SHA-256 checksum.

3. Append the checksum to the entropy.

4. Split the combined bit string into 11-bit groups.

5. Map each 11-bit group to a word from the BIP39 wordlist.

6. Display the resulting mnemonic phrase.

Tips, Edge Cases, or Limitations

Always use a hardware wallet (Trezor, Ledger) or an air-gapped device for actual cryptocurrency recovery phrases. Never use an internet-connected tool to generate mnemonics for real funds. The tool is 100% client-side, meaning no data leaves your browser, ensuring your privacy and security. For educational purposes only. Do not use this tool for real cryptocurrency recovery.

Frequently Asked Questions

A BIP39 mnemonic phrase is a human-readable seed phrase that encodes the seed for a hierarchical deterministic (HD) wallet. It is typically used for cryptocurrency wallet backups.
BIP39 entropy is a sequence of random bits that is used to generate a mnemonic phrase. The more bits of entropy, the more secure the mnemonic.
Yes, it is safe to generate a BIP39 mnemonic online using a tool like ThisDevTool. The tool is 100% client-side, meaning no data leaves your browser, ensuring your privacy and security.
A 12-word mnemonic has 128 bits of entropy, while a 24-word mnemonic has 256 bits of entropy. A 24-word mnemonic provides higher security and is recommended for real-world use.
Yes, you can use this tool to verify an existing mnemonic. Paste your mnemonic phrase into the verification mode, and the tool will check each word against the BIP39 wordlist and confirm the checksum is correct.

Quick reference

BIP39 Mnemonic Generator Quick Reference
Parameter Standard Value Word List Passphrase
Mnemonic Length 12 words BIP39 English Optional
Entropy Size 128 bits BIP39 English Enhances security
Word List 2048-word list BIP39 English Required for recovery
Seed Derivation SHA256 hash BIP39 English Optional
Security Level 128-bit security BIP39 English Recommended
Recovery Phrase 12/24-word phrase BIP39 English Optional