x402_core library
Core protocol definitions and interfaces for the x402 payment protocol.
Classes
- PaymentPayload
-
The payload sent by the client in the
payment-signature(orX-PAYMENT) header. - PaymentRequiredResponse
- The structured response body returned by a server when it requires payment (HTTP 402).
- PaymentRequirement
- Represents a specific payment option offered by a server in a 402 response.
- ResourceInfo
- Metadata about the digital resource being requested.
- SchemeClient
- Interface for payment scheme clients (e.g., "exact", "stream")
- X402Client
- A high-level HTTP client that automatically handles 402 Payment Required flows.
- X402Signer
- The interface every blockchain-specific package must implement to support signing x402 payment requirements.
Constants
- kPaymentHeader → const String
- Legacy header for payment proof (optional)
- kPaymentRequiredHeader → const String
- Standard header for payment requirements in 402 response
- kPaymentRequiredStatus → const int
- HTTP status code for payment required
- kPaymentSignatureHeader → const String
- Standard header for payment proof in request
- kX402Version → const int
- x402 protocol version
Typedefs
-
PaymentApprovalCallback
= Future<
bool> Function(PaymentRequirement requirement, ResourceInfo resource, X402Signer signer) - Callback to let the user approve a payment before it's signed and sent.
Exceptions / Errors
- InvalidPayloadException
- Invalid payment payload
- UnsupportedSchemeException
- Unsupported scheme or network
- X402Exception