- Runs it
- x402 Foundation
- Projects
- 20
- Official
- 1
- Stars checked
- 2026-11-08
- Spec
- official
x402 SDKs and Payment Tools: 20 open-source projects compared
Charge per API call or let your agent pay for one. Compare 20 open-source x402 SDKs, facilitators and paywalls by stars, licence and activity, and ship pay-per-request in days, not months.
Compare x402 projects
These 20 open-source projects implement or support x402. 1 are maintained by the official project and the rest by the community. Sort by stars or recent activity, or filter by type. These projects are listed from public GitHub data and are not scanned by AgenticMart.
vapi-network
TypeScript client for paying x402 APIs in USDC on Base
Daydreams
Agent commerce toolkit with x402 pay-per-use model access
x402-rs
Rust libraries to verify, settle and monitor x402 payments
openai-python (qntx)
OpenAI Python client with x402 payment handling added
Vybe x402 Client
Client SDK for pay-per-call access to the Vybe API over x402
r402
Rust SDK for the x402 payment protocol
openai (qntx)
OpenAI TypeScript client with x402 payment handling added
a2a-x402 TypeScript
TypeScript port of the A2A x402 payment extension
Faremeter
Framework for machine payments with pluggable x402 schemes
Stars and activity checked 2026-11-08. These projects are listed from public GitHub data and are not scanned by AgenticMart. Built one? List it free now, paid selling opens soon.
What is x402?
x402 is an open standard for internet-native payments built on the HTTP 402 Payment Required status code. A server can require payment for a request, and a client that receives a 402 response pays and retries. Coinbase created the protocol and contributed it to the x402 Foundation at the Linux Foundation, announced on April 2, 2026.
x402 vs AP2: what is the difference
x402 moves a payment over HTTP, while AP2 focuses on proving that a user authorized what an agent buys. AP2 is designed to work across payment types, and its samples include scenarios that pay with x402. The separate a2a-x402 project, listed below, combines A2A with x402, and its maintainers plan to align it with AP2. New to MCP? Read what an MCP server is.
What an x402 message looks like
When a paid resource is requested without payment, the server answers HTTP 402 with a base64-encoded PAYMENT-REQUIRED header, shown here decoded. It tells the client which payment schemes, network, asset, amount and recipient address it will accept.
{
"x402Version": 2,
"error": "PAYMENT-SIGNATURE header is required",
"resource": {
"url": "https://api.example.com/premium-data",
"description": "Access to premium market data",
"mimeType": "application/json"
},
"accepts": [
{
"scheme": "exact",
"network": "eip155:84532",
"amount": "10000",
"asset": "0x036CbD53842c5426634e7929541eC2318f3dCF7e",
"payTo": "0x209693Bc6afc0C5328bA36FaF03C514EF312287C",
"maxTimeoutSeconds": 60,
"extra": {
"name": "USDC",
"version": "2"
}
}
]
}From the official specification, checked 2026-11-12.
x402 questions
What is x402?
x402 is an open standard that lets a service charge for an API or web content directly over HTTP. It builds on the 402 Payment Required status code, so a buyer does not need an account or API key. It is licensed under Apache-2.0, and the protocol itself adds no fees beyond the payment network's own costs.
x402 vs AP2: what is the difference?
x402 moves a payment over HTTP, while AP2 focuses on proving that a user authorized what an agent buys. AP2 is designed to work across payment types, and its samples include scenarios that pay with x402. The separate a2a-x402 project, listed below, combines A2A with x402, and its maintainers plan to align it with AP2.
Which blockchains and tokens does x402 support?
As of November 2026, x402 covers EVM chains and Solana along with networks such as TON, Algorand, Stellar, Aptos, Hedera, NEAR, XRPL, Cardano and Sui. On EVM chains it works with ERC-20 tokens through EIP-3009 or Permit2. Protocol support is not the same as production support, because you also need a facilitator path for that network.
How do I get started with x402?
Add x402 payment middleware to an existing API, set the routes to charge for and give it a wallet address to receive funds. The seller quickstart in the docs tests on Base Sepolia or Solana devnet with the x402.org facilitator. Packages are available for TypeScript, Python and Go.
How does x402 work?
A server answers an unpaid request with a 402 response that says what it accepts, and the client pays and retries. The retry carries a signed payment in a PAYMENT-SIGNATURE header. The server then verifies and settles the payment, on its own or through a facilitator, and returns the resource.
Who created x402?
x402 was incubated at Coinbase, which contributed it to the x402 Foundation at the Linux Foundation on April 2, 2026. The foundation became fully operational on July 14, 2026. As of November 2026, it is run under open governance with members that include Coinbase, Google, Visa and Stripe.
Is x402 production-ready?
The x402.org FAQ describes x402 as production-ready as of November 2026, but that is the project's own statement. The same page says it has been audited and has processed millions of transactions, without giving supporting data there. Check the facilitator and network you plan to use, since production coverage varies.