BIP39 Mnemonic Phrase Generator

BIP39 Mnemonic Phrase Generator | Online Free Tool | Elysia Tools

Tool usage guide

Learn when to use this tool, what it supports, and how real users apply it.

Key facts

Category: Security
Input types: select, textarea, text
Output type: json
Sample coverage: 4
API ready: Yes

Overview

The BIP39 Mnemonic Phrase Generator is a secure utility designed to generate new 12 to 24-word mnemonic phrases or validate existing ones. It calculates entropy bits, verifies checksums, and derives the 64-byte PBKDF2-HMAC-SHA512 seed, providing essential cryptographic outputs for wallet development, testing, and key derivation workflows.

When to use

When you need to generate a secure, random 12, 15, 18, 21, or 24-word BIP39 mnemonic phrase for testing cryptocurrency wallet setups.
When validating the checksum of an existing English mnemonic phrase to ensure there are no typos or misplaced words.
When deriving the 64-byte PBKDF2-HMAC-SHA512 seed from a mnemonic and optional passphrase to debug hierarchical deterministic (HD) wallet derivation paths.

How it works

1Select the mode: either 'Generate New Mnemonic' to create a new phrase or 'Validate Existing Mnemonic' to check an existing one.
2Configure the desired word count (from 12 to 24 words) or input your existing mnemonic phrase into the text area.
3Optionally enter a BIP39 passphrase to customize the derived seed generation.
4Review the generated JSON output containing the mnemonic phrase, entropy bits, checksum validation status, and the derived PBKDF2-HMAC-SHA512 seed.

Use cases

Generating clean test vectors of various lengths (12 to 24 words) for testing HD wallet implementations.
Verifying the integrity and checksum validity of a written-down recovery phrase before importing it into a wallet.
Deriving the raw seed bytes from a mnemonic and passphrase to verify key derivation outputs in custom cryptographic scripts.

Examples

1. Generating a 24-Word Test Mnemonic with Passphrase

Blockchain Developer

Background

A developer is writing integration tests for a multi-signature wallet application and needs a valid 24-word seed phrase and its derived seed.

Problem

Generating a cryptographically valid 24-word mnemonic along with its PBKDF2-HMAC-SHA512 seed using a custom passphrase.

How to use

Set the mode to 'Generate New Mnemonic', select '24' for the word count, enter 'demo' in the passphrase field, and run the generator.

mode: 'generate', wordCount: '24', passphrase: 'demo'

Outcome

The tool outputs a JSON object containing the 24-word mnemonic, 256 bits of entropy, a valid checksum indicator, and the derived 64-byte seed.

2. Validating a 12-Word Recovery Phrase

Crypto Auditor

Background

An auditor needs to verify if a client's backup phrase is valid and has a correct checksum before performing a recovery dry-run.

Problem

Checking if a specific 12-word sequence conforms to the BIP39 standard and has a valid checksum.

How to use

FAQ

What word counts does this generator support?

It supports generating and validating standard BIP39 phrases of 12, 15, 18, 21, and 24 words.

Can I use a passphrase with my mnemonic?

Yes, you can provide an optional BIP39 passphrase to derive a unique PBKDF2-HMAC-SHA512 seed.

How does the validation mode work?

It checks if the entered words belong to the standard BIP39 English wordlist and verifies if the final checksum bit is cryptographically valid.

What cryptographic seed format is outputted?

The tool outputs a 64-byte seed derived using PBKDF2-HMAC-SHA512 with the mnemonic as the password and 'mnemonic' + passphrase as the salt.

Is this tool safe for generating production mainnet wallets?

This tool is intended for development, testing, and educational purposes; for production mainnet funds, always use a secure, offline hardware wallet.

mode: 'validate', mnemonic: 'abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon about'

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Learn when to use this tool, what it supports, and how real users apply it.

Key facts

Overview

When to use

How it works

Use cases

Examples

1. Generating a 24-Word Test Mnemonic with Passphrase

2. Validating a 12-Word Recovery Phrase

FAQ

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