Tools & demos
Interactive demos
You don't need any of this to hold Bitcoin safely. But if you've read how it all works and want to see the machinery — not just read about it — here are 11 demonstrations of what is really happening under the hood. Nothing is saved and nothing is scored: every one runs in your browser, on a seed it invents and forgets.
Every tool here generates a throwaway seed in your browser and forgets it when you leave. None of them will ever let you type your own seed words — that's the point. A site that asks for your seed is a site trying to rob you.
Why a key can't be guessed
Make 2²⁵⁶ concrete — every atom in the Earth computing since the Big Bang barely reaches a coin-flip for one key.
Open the demo →Signing — prove it, without showing the key
Sign a payment, watch anyone verify it came from your key — then try to tamper with the payment and watch the signature break.
Open the demo →One key, four address formats
Why addresses start with 1, 3, bc1q, or bc1p — all four come out of the same seed, and they're all your Bitcoin.
Open the demo →One seed, endless addresses
How one seed grows a whole tree of addresses — and how an xpub lets someone watch a wallet without ever being able to spend.
Open the demo →Multisig — why 2-of-3 works
Three keys, one wallet, any two to spend. Tap the keys and watch the threshold rule enforce itself — no single point of failure.
Open the demo →The passphrase (25th word)
Same seed, add a passphrase, land in a completely different wallet. See the decoy-vs-hidden idea for yourself.
Open the demo →BIP-85 — one seed, many seeds
How one master seed derives an endless supply of fresh, independent child seeds — back up one, re-derive the rest.
Open the demo →Split a secret into shares
The Shamir math behind SLIP-39: cut a backup into five pieces where any three rebuild it and any two reveal nothing.
Open the demo →Watch a seed get born
Generate a throwaway seed and follow it from 128 random bits — with the real SHA-256 checksum — to twelve words to a Bitcoin address.
Open the demo →Roll your own randomness
Don't trust the device's RNG? Roll a die ~50 times and hash it into a seed that's provably random by your own hand.
Open the demo →How a typo gets caught
Change one word in a throwaway seed and watch the built-in checksum catch it — and meet the rare wrong word that slips through unannounced.
Open the demo →Each one runs entirely in your browser. More may follow.
✓ Last verified: August 4, 2026