The big idea behind Keryx: write your controller once, and it works everywhere. A single action class handles HTTP requests, WebSocket messages, CLI commands, background tasks, and MCP tool calls — same inputs, same Zod validation, same middleware, same response. You write the logic once; the only thing that changes is how the request arrived and how the response gets delivered.
The fullstack TypeScript framework for MCP and APIs — write one action, serve HTTP, WebSocket, CLI, background tasks, and MCP tools.
2026-11-14
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That last transport — MCP — is the reason I built this now. Every action is automatically an MCP tool, so AI agents authenticate with built-in OAuth 2.1, get typed errors, and call the exact same validated endpoints your HTTP clients do. There's no second MCP server to maintain and no schemas to keep in sync… you expose your app to agents by writing the app.
And it's a real backend, not a toy. You get Drizzle ORM with auto-migrations, background tasks with fan-out on Resque, streaming responses (SSE, chunked binary, and the same stream over WebSocket and MCP), OpenAPI generation, pagination and caching helpers, database transactions, and a companion Vite + React frontend that reads your actions with end-to-end type safety — no code generation. It's all on Bun, so TypeScript runs natively and startup is fast.
One Action, Every Transport
Here's what that looks like in practice. This is one action:
export class UserCreate implements Action {
name = "user:create";
description = "Create a new user";
inputs = z.object({
name: z.string().min(3),
email: z.string().email(),
password: secret(z.string().min(8)),
});
web = { route: "/user", method: HTTP_METHOD.PUT };
task = { queue: "default" };
async run(params: ActionParams<UserCreate>) {
const user = await createUser(params);
return { user: serializeUser(user) };
}
}
That one class gives you:
HTTP — PUT /api/user with JSON body, query params, or form data:
Same validation, same middleware chain, same run() method, same response shape. The only thing that changes is how the request arrives and how the response is delivered.
That's it. The agent can now discover all your actions as tools, authenticate via OAuth, and call them with full type validation.
Key Components
MCP-native — every action is an MCP tool with OAuth 2.1 auth, typed errors, and per-session isolation
Transport-agnostic Actions — HTTP, WebSocket, CLI, background tasks, and MCP from one class
Zod input validation — type-safe params with automatic error responses and OpenAPI generation
bunx keryx new my-app
cd my-app
cp .env.example .env
bun install
bun dev
Requires Bun, PostgreSQL, and Redis. See the Getting Started guide for full setup instructions (including running without Postgres or Redis for quick prototypes).
Developing the framework itself
If you're contributing to Keryx, clone the monorepo instead:
git clone https://github.com/actionhero/keryx.git
cd keryx
bun install
cp example/backend/.env.example example/backend/.env
cp example/frontend/.env.example example/frontend/.env
bun dev
Production Builds
bun compile
# set NODE_ENV=production in .env
bun start
Databases and Migrations
We use Drizzle as the ORM. Migrations are derived from schemas — edit your schema files in schema/*.ts, then generate and apply:
cd example/backend && bun run migrations
# restart the server — pending migrations auto-apply
Actions, CLI Commands, and Tasks
Unlike the original ActionHero, we've removed the distinction between actions, CLI commands, and tasks. They're all the same thing now. You can run any action from the CLI, schedule any action as a background task, call any action via HTTP or WebSocket, and expose any action as an MCP tool for AI agents. Same input validation, same responses, same middleware.
Web Actions
Add a web property to expose an action as an HTTP endpoint. Routes support :param path parameters and RegExp patterns — the route lives on the action itself, no separate routes.ts file:
web = { route: "/user/:id", method: HTTP_METHOD.GET };
WebSocket Actions
Enabled by default. Clients send JSON messages with { messageType: "action", action: "user:create", params: { ... } }. The server validates params through the same Zod schema and sends the response back over the socket. WebSocket connections also support channel subscriptions for real-time PubSub.
CLI Actions
Enabled by default. Every action is registered as a CLI command via Commander. The Zod schema generates --flags and --help text automatically:
When the MCP server is enabled (MCP_SERVER_ENABLED=true), every action is automatically registered as an MCP tool. AI agents and LLM clients (Claude Desktop, VS Code, etc.) can discover and call your actions through the standard Model Context Protocol. Actions can also be exposed as MCP resources (URI-addressed data) and prompts (named templates) via mcp.resource and mcp.prompt.
Action names are converted to valid MCP tool names by replacing : with - (e.g., user:create becomes user-create). The action's Zod schema is converted to JSON Schema for tool and prompt parameter definitions.
To exclude an action from MCP tools:
mcp = { tool: false };
To expose an action as an MCP resource or prompt:
// Resource — clients fetch this by URI
mcp = { tool: false, resource: { uri: "myapp://status", mimeType: "application/json" } };
// Prompt — clients invoke this as a named template
mcp = { tool: false, prompt: { title: "Greeting" } };
OAuth 2.1 with PKCE is used for authentication — MCP clients go through a browser-based login flow, and subsequent tool calls carry a Bearer token tied to the authenticated user's session.
Fan-Out Tasks
A parent task can distribute work across many child jobs using api.actions.fanOut() for parallel processing. Results are collected automatically in Redis. See the Tasks guide for full API and examples.
Streaming Responses
Actions can stream data by returning a StreamingResponse. The framework handles SSE, chunked binary, and cross-transport behavior automatically:
Over HTTP this is native SSE; over WebSocket each chunk becomes an incremental message; over MCP chunks are forwarded as logging messages. See the Streaming guide for full details.
A Note on ActionHero
If you've used ActionHero, Keryx will feel familiar — it's the spiritual successor. I built ActionHero years ago to take the best ideas from Rails and Node.js and shove them together, and I still believe in those ideas… but the framework needed a fresh start on Bun, Zod, and Drizzle, with first-class MCP support instead of something bolted on later. Keryx is that restart.
If you're coming from ActionHero, the biggest changes are: unified controllers (actions = tasks = CLI commands = MCP tools), separate frontend and backend applications, Drizzle ORM in place of Sequelize, and MCP as a first-class transport. See the full migration guide for details.
Production Deployment
Each application has its own Dockerfile, and a docker-compose.yml runs them together. You probably won't use this exact setup in production, but it shows how the pieces fit together.
Run keryx build at image build time. It pre-generates the OpenAPI response schemas into .cache/swagger-schemas.json so the server doesn't have to derive them from your action return types on every boot:
COPY . .
RUN cd backend && bun keryx.ts build
CMD ["bun", "keryx.ts", "start"]
คัดลอกคอนฟิก stdio สำหรับ Cursor, Claude Desktop, Claude Code หรือ VS Code ได้ในหน้านี้ คอนฟิกนี้ใช้การติดตั้งของผู้เผยแพร่ ไม่ใช่พร็อกซีของ PlugMCP
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ตรวจสอบล่าสุดเมื่อ 2026-11-14 The fullstack TypeScript framework for MCP and APIs — write one action, serve HTTP, WebSocket, CLI, background tasks, and MCP tools.