Server

Mastra configures its HTTP server from a server.ts file directly under src/mastra/. The server exposes agents, workflows, and other registered primitives as REST endpoints, and the file default-exports the same ServerConfig shape you'd pass to new Mastra().

Use this page for the file-based convention. For server features, middleware, custom routes, generated API docs, and deployment behavior, see Server overview.

Quickstart

Create src/mastra/server.ts and default-export a ServerConfig object:

src/mastra/server.ts

import type { ServerConfig } from '@mastra/core/server'

export default {
  port: 4111,
  host: '0.0.0.0',
} satisfies ServerConfig

Common configurations

server.ts can configure the same server options as code registration:

Need	Use
Bind to a deployment platform address	host and port
Restrict browser access	cors
Add webhooks or health checks	apiRoutes
Enable generated API docs	build.openAPIDocs and build.swaggerUI

See Mastra server, middleware, and custom API routes for examples.

Precedence with code

Code-registered server config wins over server.ts. Routes added during startup, such as channel webhooks, are preserved when file-based server config is applied.