# HTTP 402 Paywall Protocol

### **Overview**

The **HTTP 402 Paywall Protocol** is the backbone of the 402Gate ecosystem. It extends the standard web request model with a **payment verification layer**, allowing any HTTP endpoint to enforce pay-per-use access  powered by Solana and the **$402G** token.

When a client (human user, DApp, or AI agent) requests a protected resource, the server responds with a structured `402 Payment Required` message that includes:

* the **amount** to be paid,
* the **recipient wallet address**,
* the **accepted tokens**, and
* the **unique requestId** for tracking and verification.

Once the user completes payment, the request is re-sent with proof of payment (a transaction signature) in the header. The server then verifies it on-chain and grants access immediately.

***

#### **Request–Response Cycle**

```bash
> GET /api/data
< HTTP/1.1 402 Payment Required
{
  "requestId": "req_492ab",
  "recipient": "MERCHANT_PUBKEY",
  "amount": "0.001",
  "currency": "402G",
  "acceptedMints": ["402G","USDC","SOL"],
  "instructions": "Pay the required amount and include memo=requestId"
}
```

After payment:

```bash
> GET /api/data
Payment-Proof: tx=9DgT1a...WZq3; requestId=req_492ab; payer=Fg8a...

< HTTP/1.1 200 OK
{ "result": "Access granted", "data": {...} }
```


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