What Is a Seed Phrase? How to Store and Protect It

A seed phrase is a 12 or 24 word BIP-39 backup that mathematically regenerates every private key and address in a wallet, so whoever can read those words controls the funds. The entire job is keeping it offline, durable and redundant: hand-write it, keep copies in two separate physical places, and never type it into a website, a cloud note or a support chat. Because the phrase derives a whole tree of keys, one backup covers your accounts on every chain the wallet supports — in WATS that is Ethereum, Arbitrum, Optimism, Base, Polygon, BNB Chain, Solana and TON. WATS is fully non-custodial, so the phrase is yours alone and WATS never holds a key or a copy of those words. The WATS NFC Metal Card is not where the phrase lives — it tap-authenticates to keys that stay inside the WATS apps and stores no private keys at all.

A seed phrase (also called a recovery phrase) is a list of 12 or 24 plain-English words that acts as the master backup for a crypto wallet. From those words, the wallet can regenerate every private key and address it has ever created. That means whoever holds the seed phrase controls the funds, full stop. Protecting it is the single most important job in self-custody: store it offline, keep redundant copies on durable material, and never type it into a website, share it with anyone, or let it touch the internet.

What a seed phrase actually is

When you create a non-custodial wallet, the app generates a large random number behind the scenes. That number is your true master secret. Reading and copying a raw 128- or 256-bit number by hand would be error-prone, so a standard called BIP-39 translates it into something humans can actually write down: a sequence of words drawn from a fixed list of 2,048 options.

Each word maps to a specific position in that list, and the phrase encodes a checksum over the underlying randomness. That checksum is why a wallet can reject a phrase where you have mistyped or misordered a word, rather than silently opening a stranger's empty wallet. It is a sanity check rather than a guarantee: a wrong-but-valid combination still derives a real, different wallet. A 12-word phrase carries 128 bits of entropy and a 24-word phrase carries 256 bits. Both are far beyond what any computer could guess by brute force, so the longer phrase is not meaningfully safer in practice. Order matters absolutely: the same words in a different sequence produce a completely different wallet.

From this single phrase, your wallet derives a whole tree of keys and addresses (this is the "hierarchical deterministic," or HD, wallet model). That is why one phrase can back up many accounts across many chains at once — in WATS, a single phrase stands behind your accounts on Ethereum, Arbitrum, Optimism, Base, Polygon, BNB Chain, Solana and TON. If you want the bigger picture of how keys, addresses and apps fit together, our explainer on what a crypto wallet is walks through it, and how to set up a crypto wallet covers the moment your phrase is first generated.

Why the seed phrase equals ownership

In crypto, control of the keys is control of the assets. There is no bank to call, no password-reset email, no fraud department that can claw a transfer back. Your seed phrase regenerates those keys, so in a very literal sense the phrase is your money. This is the heart of what people mean by a non-custodial wallet: you, and only you, hold the secret.

This cuts both ways, and honesty matters here. The upside is genuine sovereignty: no company can freeze your account, censor your transactions, or lose your funds in a bankruptcy. The downside is that the responsibility is entirely yours. If someone copies your phrase, they can drain your wallet from anywhere on earth without ever touching your phone. If you lose your only copy and lose access to the device, the funds are gone permanently. There is no undo button. Understanding that trade-off is the difference between feeling reckless and feeling in control.

Rule of thumb: treat your seed phrase like a bearer instrument. Possession is ownership. Anyone who can read those words can take everything.

How to store it safely

Good storage comes down to three properties: it should be offline, durable, and redundant. Offline means the words never exist as a file, photo, or message that an internet-connected device can read. Durable means the backup survives fire, water, and time. Redundant means a single accident (a house fire, a flood, a lost wallet) cannot wipe out every copy at once.

Paper vs metal

Paper is fine to start with and costs nothing, but it burns, fades, and dissolves. A folded note in a drawer is better than nothing and far better than a screenshot. For amounts you actually care about, a metal backup (a stamped or engraved stainless-steel plate) is the standard upgrade because it survives house fires and floods that would destroy paper. Many people keep a paper copy for convenience and a metal copy as the long-term anchor. Note that a stamped backup plate is a different category of object from the WATS NFC Metal Card: the plate holds words, the WATS card holds no keys and no words at all and exists to authenticate.

• Write it by hand, twice, and verify. Compare your copy word-for-word against the wallet before you fund it.
• Use at least two physical locations. For example, one copy at home and one in a safe-deposit box or a trusted relative's safe. Redundancy beats a single "perfect" hiding spot.
• Consider a passphrase (the BIP-39 "25th word") only if you understand it. It adds a layer an attacker who finds your words still cannot pass, but if you forget it, your funds are unrecoverable. Powerful, and unforgiving.
• Keep it discreet. Do not label the backup "crypto seed" or store it next to a note naming your wallet app.

For a fuller checklist that covers device hygiene, phishing defense, and transaction safety alongside backups, see our guide to crypto wallet security best practices.

What you should never do

Most stolen seed phrases are not cracked by hackers breaking math. They are handed over by the owner, usually without realizing it. The following list exists because each item is a real, common way people lose everything.

Never do this	Why it is dangerous
Take a screenshot or photo of it	Photos sync to the cloud automatically and become a target for anyone who breaches that account or your phone.
Store it in cloud notes, email, or a password manager note	Any online location can be breached, subpoenaed, or accidentally shared. The phrase must stay offline.
Type it into any website or pop-up	Legitimate wallets never ask you to enter your seed phrase on a web page. This is the number one drainer tactic.
Share it with "support" or anyone at all	No real support team, exchange, or wallet — WATS very much included — will ever ask for your seed phrase. Anyone who does is an attacker.
Keep it only on one device	A lost, stolen, or bricked phone with no backup means permanent loss.

Internalize one line and you have avoided the vast majority of seed-phrase theft: your recovery phrase is only ever entered into your own wallet app during setup or recovery, and nowhere else, ever.

How recovering a wallet works

The flip side of the seed phrase being so powerful is how easy real recovery is. Because your phrase deterministically regenerates every key, you do not need the old phone, the old app version, or even the same brand of wallet. You need the words, the right order, and a wallet that uses the same derivation paths.

1. Install a compatible BIP-39 wallet on the new device.
2. Choose "Import" or "Restore wallet" rather than "Create new."
3. Enter your 12 or 24 words in order. The checksum catches most typos.
4. If you used a passphrase, enter it too, exactly. It is case-sensitive.
5. The wallet rebuilds your accounts and shows your balances after it scans the chains.

One caveat worth knowing: if a restored wallet shows the right chains but an unfamiliar address, the phrase is almost certainly fine and the derivation path simply differs between the two apps. Most wallets let you pick or add a path during import.

A useful safety habit: practice a recovery into a fresh, empty wallet before you trust a backup with real funds. If the words restore the right empty wallet, you know your copy is correct and complete. It is far better to discover a missing word during a dry run than during an emergency.

Seed-phrase scams to watch for

Attackers know the phrase is the prize, so most crypto scams are really just attempts to get you to reveal or enter it. The mechanics change, the goal never does.

• Fake support. You post a question in a public channel and a "support agent" DMs you, walks you through a "sync" or "validation" step, and asks for your phrase. Real support never initiates DMs and never needs your words.
• Drainer websites. A search ad or lookalike domain mimics a real wallet site and shows a "verify your wallet" box asking for your seed phrase or asking you to sign a malicious transaction. Bookmark the real sites and check the URL letter by letter.
• Fake wallet apps. A counterfeit app in an app store or a sketchy APK either steals the phrase you enter or generates a wallet whose keys the attacker already controls. Only install from official links such as the WATS download page.
• "Free crypto" or airdrop traps. A site promises a reward but first asks you to "connect and verify" by importing your phrase. Connecting a wallet to a dApp never requires your seed phrase, only a signature you can read and reject.
• Pre-loaded backup cards. Be wary of any product that ships you a card or device with a seed phrase already printed inside. The seller may have a copy.

Where WATS fits

WATS is fully non-custodial across all four of its products: the Chrome extension, the mobile app, the Hot Wallet and the NFC Metal Card. You hold the keys and you hold the phrase. WATS never holds a key on your behalf, which means there is no WATS-side copy of your words to leak and no WATS-side recovery to request. That is the point of self-custody, and it is why the backup discipline above is not optional.

Two WATS specifics are worth stating plainly so nothing here is misread:

• The WATS NFC Metal Card does not store your seed phrase or your private keys. This is a common point of confusion with metal cards generally. The WATS card is a tap-to-authenticate companion, closer to a physical security key than to a cold-storage vault: the keys stay in the WATS apps, and the card proves it is you tapping. Each card carries a unique ID and pairs to exactly one device, using an NTAG 216 chip with AES-128 over ISO/IEC 14443 in a military-grade metal body rated IP68 and tested to MIL-STD-810. Your seed phrase backup is still a separate thing you write down and store offline. You can read more on the NFC card page.
• The WATS Hot Wallet is non-custodial, exactly like the mobile app and the Chrome extension. The keys are generated on your device and remain yours, and WATS never holds one. So the same single-phrase backup discipline applies to the Hot Wallet just as it does to every other WATS product.

There is also a practical reason a single phrase matters more in a multi-chain wallet. Because one WATS backup stands behind accounts on eight chains, you would normally need a native gas token on hand for each network you touch — ETH on Ethereum and its layer 2s, plus the native tokens of Polygon, BNB Chain, Solana and TON. WATS lets network fees be paid in ATS instead, using ERC-4337 account abstraction on EVM chains and LayerZero OFT to move omnichain. That is not a discount — it changes which token pays the fee, not the underlying cost — but it does mean one phrase to back up and one token to hold across the whole set.

So the protection plan for a WATS wallet is exactly the one in this article: generate the phrase in the app, write it down offline, back it up on durable material in two places, never enter it anywhere but your own wallet, and assume anyone asking for it is an attacker.

Bottom line

A seed phrase is the human-readable master key to your wallet, a 12 or 24 word backup that can rebuild every key and address you own. Because it equals ownership, the entire game is keeping it offline, durable, and redundant while never letting it touch a screenshot, a cloud, a website, or another person. Recovery is simple when you have the words and the order, and most theft comes not from hacking but from people being tricked into revealing the phrase. Learn to spot fake support, drainer sites, and counterfeit apps, and you have mastered the hardest part of self-custody. If you are setting up self-custody now, a concrete way to start is to install WATS from the download page, write down the phrase it generates before you fund anything, and keep the two WATS specifics in mind: every WATS product is non-custodial, and the NFC Metal Card authenticates rather than stores your keys.