Embedded wallets: self-custody without a seed phrase

A seed phrase is the list of words that backs up the keys of a conventional wallet, and it is where self-custody gets its hard edge: the wallet's security rests on a backup that you must keep and protect. Embedded wallets take a different route. They live inside an app and aim to give you control of your funds without asking you to manage a seed phrase or a private key. This guide explains how they work, how you get back in, what can go wrong and how the model differs from a custodial account. It uses Privy's public documentation as a worked example of how embedded-wallet providers describe their designs, because designs differ and the details sit in each provider's own docs.

What is a seed phrase, and what does it ask of you?

A seed phrase is a list of words that backs up the keys of a conventional wallet, so whoever holds the phrase can recreate the keys and control the funds. In a non-custodial wallet no company holds a copy that could restore access for you, and ethereum.org says the user is responsible for keeping their own keys secure. The phrase therefore has to stay private, and it has to stay recoverable. Embedded wallets try to remove that job from the user.

What is an embedded wallet?

An embedded wallet is a wallet created and used inside an app, so you do not need a separate wallet app, a browser extension or a seed phrase. Privy's documentation says embedded wallets need "no separate wallet client, like a browser extension or a mobile app", and that users keep custody "without needing to manage seed phrases or private keys directly."

Three things are easy to mix up. The wallet is an address on a blockchain where assets sit. The keys are the secrets that authorize transactions from that address. The app is the screen where you review and approve. In an embedded wallet the app and the key handling are built together, so the design does not ask you to manage a seed phrase. For the basic distinction between holding keys yourself and relying on a company, read custodial vs non-custodial, and for the wider topic see self-custody.

Is an embedded wallet really non-custodial?

Providers such as Privy document their embedded wallets as non-custodial: "Neither Privy nor your application ever sees a user's private key." That is a statement about one provider's design, so what matters is the architecture behind the label.

In an embedded wallet there is still infrastructure that protects key material. The question is how that infrastructure is built, and whether the design lets anyone use the key without the user's authentication. The next section sets out what Privy documents. Other providers may build their wallets differently, which is why a reader should check the provider's own documentation for each of these points: where key material lives, who can use it, how recovery works and whether export exists.

How does an embedded wallet work without a seed phrase?

It splits the private key into pieces and rebuilds the key only inside a protected environment. Privy's security architecture documents two ideas that work together.

The first is key sharding, based on Shamir secret sharing, a method of splitting a secret into shares so that no single share reveals it. Privy says "no share in isolation provides any information or access to the wallet." The second is the trusted execution environment, or TEE, an isolated environment on a server. Privy says a key is reconstructed only inside TEEs, implemented with AWS Nitro Enclaves, by combining an enclave share with an authentication share that is accessible only with valid authentication credentials. The page on embedded wallets adds that secrets are "only ever reconstituted in a secure environment under the user's control."

In plain terms, the documented design works like this:

1. The private key is split into shares, and no single share is enough to use the wallet.
2. One share sits with the enclave, and another is released only against valid authentication credentials.
3. The key is reassembled only inside the enclave.

The point of sharding is in Privy's own sentence: no share on its own provides information or access, so exposing one share does not expose the wallet.

That is why the documented design has no phrase to write down. The thing a seed phrase backs up, the key, is protected by the provider's infrastructure instead of by a piece of paper you keep. The price of that convenience is a different set of dependencies, covered below.

The difference from a custodial account lies in who can use the key. In a custodial account a company holds the keys and uses them to carry out your requests. In the design Privy documents, the key is rebuilt only inside the enclave, and only with an authentication share that needs valid credentials. Whether a given app lives up to that model depends on how it is built, which is why the questions at the end of this guide ask about key material, recovery and export.

How do you get back into an embedded wallet on a new phone?

In the setup Privy documents for its TEE wallets, you get back in with your login method. The cloud recovery page says that for apps on this setup "your users can access their accounts on other devices using their login method." It describes no other recovery mechanism for these wallets.

That makes the login the thing to protect. Reaching the wallet again needs no stored phrase, but it does need access to whatever you used to sign in. The table sets the two backup models side by side.

Can you export an embedded wallet's private key?

Yes, in the design Privy documents: Privy says users can export their wallet's private key, which it calls "an escape hatch to leave Privy at any time", and that export is restricted to wallet owners. Its export wallets page covers the mechanics.

Export matters for two reasons. It is the way out if you stop using the app or the provider, because you can take the key and use it elsewhere. It also changes your responsibility. Once you export a key you hold a secret that controls the funds, so storing it carefully becomes the same job as protecting a seed phrase, and anyone who obtains the key can control the funds at that address.

What can go wrong with an embedded wallet?

The main risks are losing access to your login, approving a transaction you did not mean to approve, and depending on a service that you do not run.

The first is covered above. The second applies to every wallet: the approval is what moves funds, so the review screen matters more than the wallet type.

The third is dependence. With an embedded wallet you rely on the provider's service to use the wallet, and export is the documented way to leave. That is a different trade-off from a seed phrase wallet, where nobody else is involved, and from a custodial account, where a company holds the keys. Neither is automatically better; they carry different risks.

What does this look like inside Neovestor?

In Neovestor, the app creates your wallets when you sign in: a Solana wallet and an Ethereum-compatible wallet, which is the one used on Base. Connecting an external wallet at sign-in is switched off, so the wallets you use are the ones the app creates.

Only you can approve transactions. Neovestor can't access your keys, its backend never derives or exports them, and it never signs as you. The only signature Neovestor's backend may add is the network fee payer signature, and only after its Transaction Guard has checked the exact transaction you approved.

The app locks with Face ID or passcode on launch and after five minutes in the background, and the lock is required to confirm a money action or to add an address-book entry. Each money action runs through a quote, a review screen, your confirmation, your signature, broadcast and status tracking. If you delete your Neovestor profile, the app warns that your funds remain in your wallet and offers export or withdrawal first.

What should you check about any embedded wallet provider?

A few questions separate one design from another, and the provider's documentation should answer each:

• Where does key material live, and can any single party use it without your authentication?
• How do you get back in on a new device, and is there any recovery path other than your login?
• Can you export the key, and who is allowed to trigger an export?
• What happens to your funds if you stop using the app?

To fund a wallet from an exchange, how to move USDC from an exchange to self-custody walks through the steps. Checking the address and the network before you send matters in every wallet.