callo
SolanaUSDCx402x402 payments, settled in USDC on Solana

Agents pay in USDC over x402. Every request pays its toll.

Launch a toll Pay one now
three agents · one booth · three paid APIs
TOLLS$0.000$0.002research-agent5.000 USDCGET /searchGET402 · $0.002$0.001trading-bot2.500 USDCGET /quoteGET$0.004scout-0712.000 USDCPOST /infer
Requests tolled
0
USDC collected
$0.000
API keys issued
0
Toll from
$0.0001
The stack every toll runs on
SolanaSettles onSolana
USDCPays inUSDC
x402Speaksx402
PhantomSigns withPhantom
JupiterRoutes viaJupiter
pump.funLaunches onpump.fun
xStocksPairs withxStocks
How a toll works


The agent asks, the booth names a price, the agent pays it on Solana, the request goes through. The whole exchange is plain HTTP your agent already speaks.

agent@solana ~ x402request
$ curl -i https://usecallo.app/api/x402/sol-price
> GET /api/x402/sol-price HTTP/1.1
> Host: usecallo.app
Anatomy of a toll

Seven layers, from the HTTP call down to the Solana slot it settles in. Watch it come apart, get checked layer by layer and snap back together.

CL-402
Toll request / anatomyexploded view · one paid call · 7 layers
TOLL
$0.001
1,000 µUSDC · 6 dp
SETTLE
0 ms
COMPUTE
— CU
SLOT
Solana slot
landed · ~400 ms
01 finality
SIG
ed25519 signature
5Hk2…9xQa
02 agent key
IX
TransferChecked
1,000 µUSDC → vault
03 spl-token
HDR
X-PAYMENT
eyJ4NDAyVmVyc2lv…
04 base64 json
402
Payment Required
exact · solana · USDC
05 the quote
REQ
GET /api/x402/…
no key · no account
06 http/1.1
200
200 OK + receipt
X-PAYMENT-RESPONSE
07 served
ASSEMBLED
SUBSYSTEMS
  • 200 OK + receipt··
  • GET /api/x402/…··
  • Payment Required··
  • X-PAYMENT··
  • TransferChecked··
  • ed25519 signature··
  • Solana slot··
DISPLAY
requestquotesignsettleserve
For APIs

Put a price on any endpoint. Keep your code.

  • Launch it here, point it at your URL, set a toll per call.
  • Agents call the booth; paid requests are forwarded to you untouched.
  • No billing system, no keys to rotate, no chargebacks.
// Your API stays exactly as it is.
// Agents call the booth instead:
GET https://usecallo.app/api/x402/<TOLL>/v1/search?q=solana

// Once the toll is paid, the booth forwards to:
GET https://api.your-app.com/v1/search?q=solana
For agents

A wallet is the only credential.

  • Discover a toll, read its price from the 402, decide if it is worth it.
  • Pay in USDC for exactly what you use, down to a hundredth of a cent.
  • Works with any x402 client, or twenty lines of your own.
// 1. call: the booth answers 402 with the price
let res = await fetch(TOLL)
const { accepts: [req] } = await res.json()

// 2. pay: a USDC transfer for exactly that amount
const tx = await usdcTransfer(wallet, req.payTo, req.maxAmountRequired)
const payment = btoa(JSON.stringify({
  x402Version: 1, scheme: 'exact', network: 'solana',
  payload: { transaction: tx },
}))

// 3. retry: same request, payment attached
res = await fetch(TOLL, { headers: { 'X-PAYMENT': payment } })
Launchpad

Launch an endpoint.

Deploy in one signatureYour toll gets a gateway URL, a vault and a pump.fun coin. You sign once in Phantom.
One vault, two income streamsUSDC from every paid call and SOL creator fees from the coin both land in the toll’s vault.
Stock pairingPick up to three xStocks and a share. That cut of every dollar is swapped into NVDAx, TSLAx, SPYx and friends and held.
The rest is yoursWhatever isn’t paired is paid out to the wallet that launched the toll.
Open the launchpad
$QUOTExStock Quotes · $0.002 / call
vault
x402 tollsUSDC per callcreator feesSOL from tradingtoll vaultbuilder 60%paid outstocks 40%NVDAx · TSLAx, held
Stock pairing 40% of every dollar the vault earns
Toll board

Tolls
0
Paid calls
0
Collected
$0
Loading the board…
See every toll
Playground

These are real endpoints on this site. Send a request, watch the gate quote a price, pay it, get the data.

Loading tolls…
402
The HTTP status code reserved for payments since 1997. Finally in use.
$0.0001
Smallest toll you can charge. Priced in USDC, 6 decimals.
~400ms
A Solana slot. Fast enough to settle inside the request.
0
API keys, accounts or invoices. The payment is the auth.
Questions

What is x402?+

HTTP has had a status code for payments since 1997: 402 Payment Required. x402 is the open standard that finally uses it. The server quotes a price, the client pays in a stablecoin, and retries the same request with the payment attached. No accounts, no API keys, no invoices.

Why Solana?+

A toll is often a fraction of a cent. That only works on a chain where the network fee is smaller than the toll and settlement takes well under a second. Solana does both, and USDC is native there.

What does an agent need to call a toll?+

A Solana wallet with a little USDC. It calls the URL, reads the 402, signs a USDC transfer for the exact amount and retries. Every x402-aware client does this automatically.

What happens when I launch on the launchpad?+

Your endpoint gets a toll gate URL and its own vault, and a pump.fun coin is deployed for it with the vault as creator. Tolls paid in USDC and the coin’s creator fees both land in that vault.

What is stock pairing?+

You choose up to three tokenized stocks (Backed xStocks such as NVDAx, TSLAx or SPYx) and a percentage. That share of everything the vault earns is swapped into those stocks through Jupiter and held in the vault. The rest is paid out to your wallet.

Is this live?+

Yes. Payments settle in real USDC on Solana mainnet and launches deploy real pump.fun coins.

Open the gate

Launch your endpoint, set the price, pair it with a stock. Agents do the rest.

Launch a toll Read the docs