A way for a website or API to charge for a request. It answers “402 Payment Required” with the price; the caller pays and asks again, and gets the result.

Does my agent ever see the wallet’s key?

No. The key stays with the helper app on your computer. Your agent asks the helper app to pay, and gets back a signed payment to send, never the key.

Can my agent spend more than I allow?

Not without you. A payment to a payee you haven’t listed, over your daily limit, or on a network you haven’t allowed waits for your approval. A new wallet’s limit is $0, so until you set one, every payment asks you.

Which currencies and networks work?

USDC on Base and on Solana, plus their test networks (Base Sepolia and Solana devnet). Other tokens and networks are refused.

Does a limit put money in the wallet?

No. The limit only caps what the helper app will sign. The wallet needs its own USDC; if there isn’t enough, the service can’t collect the payment.

Does Wundervault charge a fee?

No. Your agent pays the service’s price, and Wundervault adds nothing.

What if two computers use the same wallet?

Each computer counts its own daily limit, so two computers with a $5 limit can spend $10 between them.

Agent payments

Let your agent pay.
Keep the wallet.

More and more web services charge per request, using x402: the service answers "payment required" with a price, the agent pays a few cents in USDC, and gets the result. Wundervault lets your agent do that without ever holding your wallet's key. A helper app on your computer signs each payment inside the rules you set; other USDC payments wait for you, and ones it can't make are refused.

Get started Your rules

How it works

One payment, start to finish.

Your agent asks a service for something. The service says what it costs.
Your agent asks the helper app to pay. The wallet stays with the helper app.
The helper app checks your rules. Anything outside them waits for you.
The helper app signs the payment. Your agent sends it and gets the result.

Your rules

You decide what it may spend.

You set these on the wallet in your vault. They're encrypted in your browser, so our server stores them but can't read or change them. Or set the wallet to "ask me first", and every payment asks you.

A daily limit
An amount in dollars, counted over any 24 hours on each computer. A new wallet starts at $0, so every payment asks you until you set one.
Payees you trust
The addresses your agent may pay without asking. Payments to anyone else wait for you, and you can approve one and add the payee in a single step.
Networks you allow
A Base wallet pays on Base, a Solana wallet on Solana, and each can also use its test network. Tick which. A payment on one you haven't ticked waits for you; any other network is refused.
Your wallet, checked
You give the wallet's address. The helper app checks it's the address your key controls, and refuses to pay if it isn't.

When a payment needs you

You see exactly what you're paying.

What you're shown

The amount, who it goes to, the network, what it's for as the service describes it, and why it's asking you: a payee you haven't listed, over today's limit, or a network you haven't ticked.

What you can do

Allow it once, allow it and add the payee to your trusted list, or decline. Your agent waits for your answer, and can keep waiting if you haven't decided yet.

Only you can approve

Approving needs your vault unlocked, because your browser seals the approval to exactly what you saw. Our server can delay an approval; it can't make one.

Privacy

What we see, and what stays with you.

We see

That a payment happened. Once every computer on your account runs the new version and no secret is still set up the version-1 way, your next unlock locks away names and setups. After that, we see agent and wallet IDs, not wallet names or setups. We still see which agent has which key, its approval tier, a wallet-or-signer note, padded counts and sizes, timing, and computer and agent versions.
The payee and amount only while you're being asked. They're erased when you decide.

We can't see

Your wallet's key. After locking, wallet names are also sealed with a key only your vault has. Emails omit key names unless you enable "Name my keys in emails". A lost vault loses names as well as values.
Your rules: your limit and your payees
Who a payment inside your rules went to

Kept on your computer

Every payment the helper app signed, with the payee, amount, network and your agent's reason, in its signed log

What works today

Supported, and not yet.

Works

x402 payments (versions 1 and 2) in USDC, a dollar-backed digital currency, on the Base and Solana networks. Base Sepolia and Solana devnet for testing.

Not yet

Other tokens and networks, and payments that need a separate approval step on the blockchain first. The helper app refuses these rather than guessing. Need one? Tell us.

Signing keys, too

A signing key signs only what you approve, one signature at a time. You see the text being signed when it's up to 64 KB, and its size and fingerprint otherwise.

Our first payment was $0.01 in test USDC on Base Sepolia, made by an agent that never saw the wallet's key (the transaction). Back then you approved every payment by hand; now the helper app pays inside your rules.

Questions

What is x402?: A way for a website or API to charge for a request. It answers “402 Payment Required” with the price; the caller pays and asks again, and gets the result.
Does my agent ever see the wallet’s key?: No. The key stays with the helper app on your computer. Your agent asks the helper app to pay, and gets back a signed payment to send, never the key.
Can my agent spend more than I allow?: Not without you. A payment to a payee you haven’t listed, over your daily limit, or on a network you haven’t allowed waits for your approval. A new wallet’s limit is $0, so until you set one, every payment asks you.
Which currencies and networks work?: USDC on Base and on Solana, plus their test networks (Base Sepolia and Solana devnet). Other tokens and networks are refused.
Does a limit put money in the wallet?: No. The limit only caps what the helper app will sign. The wallet needs its own USDC; if there isn’t enough, the service can’t collect the payment.
Does Wundervault charge a fee?: No. Your agent pays the service’s price, and Wundervault adds nothing.
What if two computers use the same wallet?: Each computer counts its own daily limit, so two computers with a $5 limit can spend $10 between them.

Get started For agents