Build Apps for AI with an Express-like API

No protocol knowledge required. Write a function — the framework and platform handle the rest.

import { createServer, T } from "@mctx-ai/app";

const app = createServer({
  instructions: "A greeting server. Use the greet tool to say hello.",
});

function greet({ name }) {
  return `Hello, ${name}!`;
}
greet.description = "Greet someone by name";
greet.input = {
  name: T.string({ required: true, description: "Name to greet" }),
};
app.tool("greet", greet);

export default { fetch: app.fetch };

That's a working App for AI. The framework handles protocol negotiation, input validation, error sanitization, CORS, and capability detection.

import { createServer, T } from "@mctx-ai/app";

const app = createServer({ ... });

async function getPreferences(params, ctx) {
  // ctx.userId is stable — same user gets same ID across all devices on your server
  const prefs = await db.get(`prefs:${ctx.userId}`);
  return prefs ?? defaultPreferences;
}
getPreferences.description = "Get preferences for the current user";
app.tool("getPreferences", getPreferences);

No auth code needed. mctx authenticates every subscriber before the request reaches your handler. ctx.userId is always present, always verified, always the same for the same user — across every client and every session.

• Global hosting

  Runs on Cloudflare's edge. No servers to manage, no scaling to configure.

• Authentication

  Every subscriber is authenticated automatically. Zero auth code in your server.

• Payments & billing

  Stripe is fully wired. You earn 80% of every request.

• Versioned endpoints

  Pin to /v1.2.3 for CI stability, /v1 for latest major, or go versionless for always-latest. Sessions lock to the resolved version — no surprise upgrades mid-connection.

• Your own subdomain

  yourserver.mctx.ai is yours the moment you deploy.

• Discovery publishing

  Auto-published to the MCP Community Registry and Context7 — so your App is instantly discoverable by AI assistants and developers alike.

• HTTPS & TLS

  Handled. Always.

• Subscription management

  Subscriber flows, cancellations, and enforcement handled end-to-end.

• Only on mctx

• Any AI client

  Claude, Cursor, Copilot, Codex, OpenClaw — ctx.userId is the same no matter which tool the user connects from.

• Any machine

  Laptop, phone, or IDE — the identity follows the user, not the device. Scope storage and state to the person, not the session.

• Any session

  Sessions end. Identity doesn't. Every new connection resolves to the same ctx.userId, so your server always picks up where it left off.

• One identity, everywhere

  Once authenticated on mctx, a subscriber's identity is centralized and persistent. Your server knows who is calling — always.