http 402 payment enforcement middleware
Implements RFC 7231 HTTP 402 Payment Required status code enforcement as Express middleware, intercepting requests to MCP tool servers and validating payment credentials before allowing tool execution. Uses OWS CLI integration to verify payment state and enforce monetization policies at the HTTP layer, blocking unpaid requests with 402 responses and payment metadata.
Unique: Native HTTP 402 enforcement at the MCP server boundary using OWS CLI integration, enabling payment gates without modifying individual tool implementations or requiring custom authentication schemes
vs alternatives: Directly implements RFC 7231 HTTP 402 standard for payment enforcement rather than layering payments on top of OAuth/JWT, making it natively compatible with HTTP-aware clients and proxies
usdc payment processing on base chain
Integrates USDC stablecoin payments on the Base blockchain through OWS CLI, enabling tool servers to accept and validate on-chain payments without directly managing wallet keys or smart contracts. Abstracts blockchain interaction complexity by delegating to OWS CLI's payment verification and settlement logic.
Unique: Abstracts Base chain USDC payments through OWS CLI, eliminating need for direct ethers.js/web3.js integration or smart contract deployment while maintaining on-chain settlement guarantees
vs alternatives: Simpler than building custom smart contracts or using general payment processors because it's purpose-built for MCP monetization and handles blockchain complexity via CLI abstraction
ows cli integration and payment validation
Provides a Node.js wrapper around OWS CLI commands for payment validation, executing CLI subcommands to check payment status, retrieve payment metadata, and enforce monetization policies. Uses child_process spawning to invoke OWS CLI with structured arguments and parses JSON responses for payment state verification.
Unique: Wraps OWS CLI as a Node.js integration layer, allowing MCP servers to leverage OWS payment infrastructure without requiring direct SDK dependencies or blockchain libraries
vs alternatives: Lighter-weight than full SDK integration because it delegates all payment logic to OWS CLI, reducing bundle size and dependency surface area
express middleware factory for payment gates
Exports a middleware factory function that creates Express middleware instances configured with specific payment requirements (amount, currency, recipient). Middleware intercepts requests, validates payment state via OWS CLI, and either forwards requests to downstream tools or returns 402 responses with payment instructions.
Unique: Factory pattern middleware that creates configured payment gates for Express, allowing per-route payment policies without monolithic middleware configuration
vs alternatives: More flexible than hardcoded payment checks because it's a reusable middleware factory, enabling different payment amounts for different tool endpoints
payment metadata extraction and response formatting
Parses OWS CLI responses and formats payment metadata (transaction hash, amount, timestamp, payer address) into HTTP response headers and JSON bodies for 402 Payment Required responses. Structures payment instructions in a standardized format that clients can use to complete payment and retry requests.
Unique: Standardizes payment metadata extraction from OWS CLI into HTTP 402 response format, enabling interoperability between MCP servers and payment-aware clients
vs alternatives: Provides structured payment instructions in HTTP responses rather than opaque error messages, making it easier for clients to understand and complete payment flows
monetization policy enforcement
Enforces configurable monetization policies at the MCP server level, including minimum payment amounts, payment recipient addresses, and currency requirements. Policies are applied per-middleware instance and validated against incoming requests before tool execution is allowed.
Unique: Applies monetization policies at the HTTP middleware layer, enforcing payment requirements before requests reach MCP tool logic, enabling transparent payment gates
vs alternatives: Cleaner separation of concerns than embedding payment logic in tool code because policies are enforced at the server boundary