One backup, many accounts
Early crypto wallets kept a loose bag of random private keys — lose the file, lose the coins, and every new address meant a new backup. Modern wallets solved this with a deceptively simple idea: generate every key you will ever need from one master secret, deterministically. That is the HD wallet — hierarchical deterministic — and it is why a single seed phrase written on paper can restore dozens of accounts across multiple blockchains, years later, in software that has never seen them before.
From words to master seed: BIP-39
The seed phrase itself comes from a standard called BIP-39. The wallet draws random entropy, maps it onto a fixed wordlist, and hands you 12 or 24 words with a built-in checksum. Run through a key-stretching function, those words become a large binary master seed. Two properties matter: the words are not the keys — they are the recipe for them — and the process is one-way and reproducible. Any BIP-39 wallet, fed the same words, computes the same master seed, forever. That is what makes the phrase a complete backup, and why we treat protecting it as the core habit of self-custody in our seed phrase guide.
The derivation tree: BIP-32
From that master seed, BIP-32 defines how to grow a tree of keys. The master key deterministically derives child keys, children derive grandchildren, and every branch is reproducible from the root. The hierarchy is what lets one secret serve unlimited structure: separate accounts for saving and spending, a fresh receive address for every payment, entire chains on their own branches — all recoverable from the same 12 or 24 words, with nothing new to back up, ever.
Derivation paths: the address of an address
A derivation path — the cryptic string like m/44'/60'/0'/0/0 you may have seen in advanced settings — is simply directions through that tree: which purpose, which coin, which account, which index. BIP-44 standardized the layout, assigning each blockchain its own coin number so an Ethereum branch and a Solana branch never collide. Different ecosystems also use different signature schemes under the hood (Solana's keys, for example, come from a different curve than Ethereum's), but the principle holds across all of them: seed plus path equals key, every time.
What an xpub reveals
The tree has one more trick: extended public keys. An xpub lets software derive all the public addresses of a branch — but none of the private keys. That enables watch-only portfolio views and receiving addresses generated on an offline device's behalf. The caveat is privacy, not security: anyone holding your xpub can see every address in that branch and link them together. Share it the way you would share a full statement of that account, because functionally it is one.
Same seed, different addresses?
A classic support mystery: you import your seed into another wallet and the balance looks empty. Almost always, nothing is lost — the second wallet is walking a different path through the same tree, or deriving for a different chain by default. The funds sit exactly where they always were, at the branch the original wallet used. This is also the honest caveat about "universal" backups: the seed standard is shared, but path conventions vary between wallets, so restoring works most smoothly in the wallet family that created the seed — or one that scans the common paths for you.
How WATS uses this
The HD design is what makes a true multi-chain wallet possible, and WATS leans on it fully: one backup, one identity, with EVM, Solana and TON accounts derived on their proper branches — the experience we describe in managing Ethereum, Solana and TON in one wallet. WATS is non-custodial end to end: the seed and every key derived from it exist only on your side, and WATS never holds a key. The fee layer is then unified to match: every action — transfers, swaps, staking — is charged in one token, ATS, instead of each chain's native gas, via an ERC-4337 paymaster on EVM and an equivalent fee-payer/relayer on Solana and TON. ATS is a LayerZero OFT, so a single balance spans all three ecosystems, and collected ATS is burned from a 100M supply toward a 30M floor. WATS is the first and only wallet to combine ERC-4337 and OFT single-token fees with that burn — mechanics on the ATS fee page.
Frequently asked questions
Can one seed phrase really back up all my chains and accounts?
Yes — that is the point of the HD design. The seed deterministically generates a tree of keys, with separate branches per blockchain and per account, so every address a wallet creates for you is recoverable from the same 12 or 24 words. The flip side is concentration of risk: whoever holds the phrase can rebuild the entire tree, so the seed deserves your strongest protection.
Why does my seed show different addresses in a different wallet?
Because the second wallet is deriving along a different path or for different chains by default, not because your funds moved. Seed plus derivation path determines the key; wallets agree on the seed standard (BIP-39) but differ in path conventions. Your assets remain at the addresses the original wallet derived — restoring in that wallet, or in one that scans common paths, brings them back into view.
Is sharing an xpub dangerous?
It cannot lose you funds — an extended public key derives only addresses, never private keys, so it enables watch-only views at most. What it does cost is privacy: the holder can enumerate every address on that branch and link your activity together. Treat an xpub like a live, complete statement of that account and share it only with services you would trust with that information.