HTTP 402 · x402 protocol · Machine Payments Protocol

Let your AI agent
pay for data on-chain.

jaypay is the open payment layer for the agentic web. Sellers monetize their APIs in minutes. Buyers let their AI agents pay transparently on the blockchain — no middleman, full audit trail.

I'm a Seller →I'm a Buyer →Browse Directory
▶ pay.fetch https://news-ep.com/api/v1/stories?market=houston
↳ 402 Payment Required — $0.005 USDC on Base
↳ signing EIP-3009 permit with wallet...
↳ settlement confirmed · tx 0xd091...
↳ 200 OK — {"stories": [...], "market": "houston"}
▶ pay.wallet_status
today spent: $0.005 USDC
daily cap: $1.00 USDC
chain: Base mainnet · Solana mainnet

How it works

01
Agent requests data
Your AI calls a URL. The API responds with a 402 — payment required.
02
Gateway pays
jaypay's buyer agent handles the 402 automatically. Signs a USDC transaction. The AI never sees the wallet.
03
Blockchain settles
The transaction is broadcast to Base or Solana. Confirmed in seconds. The receipt is public and permanent.
04
Data delivered
The seller confirms payment on-chain and returns the response. Full audit trail on the ledger.

Two tools. One system.

thesellside-x4-agent

seller

Drop the Python SDK into your FastAPI app. Define your prices. Install the middleware. Your API now speaks x402 and MPP — any AI agent with jaypay can pay you on-chain.

▶ pip install jaypay
# two lines to go live:
install_x402(app)
install_mpp_middleware(app)
Seller install guide →

thebuyside-x4-agent

buyer

One command adds three tools to your AI agent: discover paid APIs, fetch and pay automatically, check wallet status. Supports Base and Solana. Agent never touches a private key.

▶ claude mcp add x402-pay --
npx -y thebuyside-x4-agent
# tools now available:
pay.fetch · pay.discover · pay.wallet_status
Buyer install guide →
WHY ON-CHAIN

Money that speaks for itself.

Traditional payment rails hide the flow of money inside bank records that belong to the bank. Every jaypay transaction is recorded on a public blockchain — the receipt is a hash anyone can verify, forever. No institution controls it. No audit requires a request.

As AI agents begin spending money on behalf of humans, that transparency becomes essential. You should always be able to answer: where did that money go, when, and did I authorize it. The blockchain answers that cleanly.

Ready to list your API?

If you have an x402 or MPP-enabled endpoint, submit it to the directory. Any agent running jaypay can discover and pay it automatically.

Submit your API →