One frozen contract.Every stack.

Express

Express middleware for pay-per-request access control using the x402 protocol. Drop one middleware in front of any route — agents pay in USDC, keys/fees/settlement live on the platform. Thin client: signs requests, interprets challenge/verify, fails closed.

Next.js App Router (Edge-safe)

Thin x402 payment gate for Next.js (App Router). Edge-runtime safe — Web Crypto / fetch only, no node:*. Relays to the platform's signed challenge/verify and fails closed: if the platform is unreachable the route returns 502 and never serves paid content.

FastAPI (Python ≥ 3.10)

Thin FastAPI client for the x402 paywall platform. Implements the frozen X402v1 wire contract. No settlement logic — relays to the platform's signed challenge/verify and fails closed: if the platform is unreachable the gated route returns 502 and never serves paid content.

Laravel 10 (PHP ≥ 8.1)

Thin x402 payment-gate middleware for Laravel apps. Implements the frozen X402v1 wire contract. A client SDK for your Laravel app — distinct from the platform backend. Relays to the platform's signed challenge/verify and fails closed: if the platform is unreachable the route returns 502 and never serves paid content.

Go ≥ 1.21 (stdlib net/http)

Thin stdlib-only net/http x402 payment gate for Go. Implements the frozen X402v1 wire contract. Zero external dependencies. Relays to the platform's signed challenge/verify and fails closed: if the platform is unreachable the route returns 502 and never serves paid content.

Spring Boot 3 (Java 17+)

Thin x402 payment-gate filter for Spring Boot. Implements the frozen X402v1 wire contract. No payment logic in your app; relays to the platform's signed challenge/verify and fails closed (502, never serves paid content if the platform is unreachable).

ASP.NET Core (.NET 8)

Thin x402 payment-gate middleware for ASP.NET Core. Implements the frozen X402v1 wire contract. No payment logic in your app; relays to the platform's signed challenge/verify and fails closed (502, never serves paid content if the platform is unreachable).

Ruby on Rails (Rack)

Thin x402 payment-gate Rack middleware for Rails. Implements the frozen X402v1 wire contract. No payment logic in your app; relays to the platform's signed challenge/verify and fails closed (502, never serves paid content if the platform is unreachable).

Django (Python ≥3.10)

Thin x402 payment-gate middleware for Django. Implements the frozen X402v1 wire contract. No payment logic in your app; relays to the platform's signed challenge/verify and fails closed (502, never serves paid content if the platform is unreachable).