Seed Tool

A seed tool is offline software for generating, verifying, or converting BIP 39 mnemonic seeds without trusting a hardware wallet or online generator for the randomness. Common operations:

• Generate a seed from physical entropy. Roll 99 dice (giving 128+ bits of true randomness) and feed the rolls into the tool; out comes the matching 12 or 24-word phrase. No software RNG involved at any point.
• Convert between formats. BIP 39 words to raw entropy and back. Useful for verifying that two backups (printed words and stamped metal) encode the same seed.
• Verify a checksum. Confirm a written-down 24-word phrase is internally consistent before relying on it.
• Test an optional passphrase. Compute the derived seed for a given (mnemonic + passphrase) pair and verify it produces the expected addresses.

Real implementations:

• SeedSigner. Stateless air-gapped device that takes dice rolls, produces a seed, and signs PSBTs without ever persisting the seed.
• Coldcard's BIP 39 entropy tool. Built into the device firmware; supports dice, cards, and other entropy sources.
• Ian Coleman's open-source BIP 39 tool. Runs in a browser, but designed to be downloaded and used offline. Used to verify seeds, derive addresses, and sanity-check wallet behavior.
• Various Python / Rust CLI tools. For developers who want to verify what their wallet is doing or build custom backup workflows.

The discipline that makes a seed tool useful: run it on an air-gapped machine (or a dedicated trusted device), use the verified open-source version, and confirm the output matches what your wallet sees before trusting any meaningful amount to the resulting seed.