Documentation Index
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The exact scheme is a fixed-price payment scheme. The seller advertises one amount, the buyer signs for that exact amount, and the facilitator settles that payment for the request.
Use exact when the final charge is known before the response is generated, such as a fixed-price API call, file download, or gated page.
Server Setup
import { HTTPFacilitatorClient } from "@x402/core/server";
import { paymentMiddleware, x402ResourceServer } from "@x402/express";
import { ExactEvmScheme } from "@x402/evm/exact/server";
import { ExactSvmScheme } from "@x402/svm/exact/server";
const facilitatorClient = new HTTPFacilitatorClient({
url: "https://x402.org/facilitator",
});
const resourceServer = new x402ResourceServer(facilitatorClient)
.register("eip155:84532", new ExactEvmScheme())
.register("solana:EtWTRABZaYq6iMfeYKouRu166VU2xqa1", new ExactSvmScheme());
app.use(
paymentMiddleware(
{
"GET /weather": {
accepts: [
{
scheme: "exact",
price: "$0.001",
network: "eip155:84532",
payTo: "0xYourAddress",
},
{
scheme: "exact",
price: "$0.001",
network: "solana:EtWTRABZaYq6iMfeYKouRu166VU2xqa1",
payTo: "YourSolanaAddress",
},
],
description: "Weather data",
mimeType: "application/json",
},
},
resourceServer,
),
);
routes := x402http.RoutesConfig{
"GET /weather": {
Accepts: x402http.PaymentOptions{
{
Scheme: "exact",
Price: "$0.001",
Network: "eip155:84532",
PayTo: "0xYourAddress",
},
{
Scheme: "exact",
Price: "$0.001",
Network: "solana:EtWTRABZaYq6iMfeYKouRu166VU2xqa1",
PayTo: "YourSolanaAddress",
},
},
Description: "Weather data",
MimeType: "application/json",
},
}
handler := nethttpmw.X402Payment(nethttpmw.Config{
Routes: routes,
Facilitator: facilitatorClient,
Schemes: []nethttpmw.SchemeConfig{
{Network: x402.Network("eip155:84532"), Server: exactevm.NewExactEvmScheme()},
{Network: x402.Network("solana:EtWTRABZaYq6iMfeYKouRu166VU2xqa1"), Server: exactsvm.NewExactSvmScheme()},
},
})(mux)
from fastapi import FastAPI
from x402.http import FacilitatorConfig, HTTPFacilitatorClient, PaymentOption
from x402.http.middleware.fastapi import PaymentMiddlewareASGI
from x402.http.types import RouteConfig
from x402.mechanisms.evm.exact import ExactEvmServerScheme
from x402.mechanisms.svm.exact import ExactSvmServerScheme
from x402.server import x402ResourceServer
app = FastAPI()
facilitator = HTTPFacilitatorClient(FacilitatorConfig(url="https://x402.org/facilitator"))
server = x402ResourceServer(facilitator)
server.register("eip155:84532", ExactEvmServerScheme())
server.register("solana:EtWTRABZaYq6iMfeYKouRu166VU2xqa1", ExactSvmServerScheme())
routes = {
"GET /weather": RouteConfig(
accepts=[
PaymentOption(
scheme="exact",
price="$0.001",
network="eip155:84532",
pay_to="0xYourAddress",
),
PaymentOption(
scheme="exact",
price="$0.001",
network="solana:EtWTRABZaYq6iMfeYKouRu166VU2xqa1",
pay_to="YourSolanaAddress",
),
],
description="Weather data",
mime_type="application/json",
),
}
app.add_middleware(PaymentMiddlewareASGI, routes=routes, server=server)
Client Setup
import { x402Client } from "@x402/core/client";
import { ExactEvmScheme } from "@x402/evm/exact/client";
import { ExactSvmScheme } from "@x402/svm/exact/client";
import { createKeyPairSignerFromBytes } from "@solana/kit";
import { base58 } from "@scure/base";
import { privateKeyToAccount } from "viem/accounts";
const evmSigner = privateKeyToAccount(process.env.EVM_PRIVATE_KEY as `0x${string}`);
const svmSigner = await createKeyPairSignerFromBytes(
base58.decode(process.env.SVM_PRIVATE_KEY!),
);
const client = new x402Client();
client.register("eip155:*", new ExactEvmScheme(evmSigner));
client.register("solana:*", new ExactSvmScheme(svmSigner));
import (
x402 "github.com/x402-foundation/x402/go"
exactevm "github.com/x402-foundation/x402/go/mechanisms/evm/exact/client"
exactsvm "github.com/x402-foundation/x402/go/mechanisms/svm/exact/client"
evmsigners "github.com/x402-foundation/x402/go/signers/evm"
svmsigners "github.com/x402-foundation/x402/go/signers/svm"
)
evmSigner, err := evmsigners.NewClientSignerFromPrivateKey(os.Getenv("EVM_PRIVATE_KEY"))
if err != nil {
log.Fatal(err)
}
svmSigner, err := svmsigners.NewClientSignerFromPrivateKey(os.Getenv("SVM_PRIVATE_KEY"))
if err != nil {
log.Fatal(err)
}
x402Client := x402.Newx402Client().
Register("eip155:*", exactevm.NewExactEvmScheme(evmSigner, nil)).
Register("solana:*", exactsvm.NewExactSvmScheme(svmSigner))
import os
from eth_account import Account
from x402 import x402Client
from x402.mechanisms.evm import EthAccountSigner
from x402.mechanisms.evm.exact.register import register_exact_evm_client
from x402.mechanisms.svm import KeypairSigner
from x402.mechanisms.svm.exact.register import register_exact_svm_client
client = x402Client()
account = Account.from_key(os.getenv("EVM_PRIVATE_KEY"))
register_exact_evm_client(client, EthAccountSigner(account))
svm_signer = KeypairSigner.from_base58(os.getenv("SVM_PRIVATE_KEY"))
register_exact_svm_client(client, svm_signer)
Network Implementations
The exact scheme has network specifications for EVM, SVM, AVM, Stellar, Aptos, Hedera, TON, Cardano, Keeta, and Sui.
EVM Transfer Methods
The EVM implementation supports two transfer methods:
| Method | Description |
|---|
eip3009 | Uses token-native transferWithAuthorization, commonly for USDC. This is the default when supported. |
permit2 | Uses Uniswap Permit2 plus the x402 exact proxy, so it can support ERC-20 tokens without EIP-3009. |
Examples
Specs
See Also