registerApiRoute()

The registerApiRoute() function creates custom HTTP routes that integrate with the Mastra server. Routes can include OpenAPI metadata to appear in the Swagger UI documentation.

Import

import { registerApiRoute } from '@mastra/core/server'

Parameters

path

The URL path for the route. Supports path parameters using :param syntax.

registerApiRoute("/items/:itemId", { ... })

Note: Custom route paths can't start with the server's configured apiPrefix (default: /api), as that prefix is reserved for built-in Mastra routes. If you set a custom apiPrefix, only that prefix is reserved — for example, with apiPrefix: '/mastra/api', paths like /api/my-endpoint are allowed.

options

method:

'GET' | 'POST' | 'PUT' | 'DELETE' | 'PATCH' | 'ALL'

HTTP method for the route

handler?:

Handler

Route handler function receiving Hono Context. Use either `handler` or `createHandler`, not both.

createHandler?:

(c: Context) => Promise<Handler>

Async factory function to create the handler. Use either `handler` or `createHandler`, not both.

middleware?:

MiddlewareHandler | MiddlewareHandler[]

Route-specific middleware functions

cors?:

CorsOptions

Route-specific CORS configuration. Use this when one custom route needs a different cross-origin policy from `server.cors`.

openapi?:

DescribeRouteOptions

OpenAPI metadata for Swagger UI documentation

OpenAPI options

The openapi property accepts standard OpenAPI 3.1 operation fields from hono-openapi. Routes without an openapi property aren't included in Swagger UI.

summary?:

string

Short summary of the operation

description?:

string

Detailed description of the operation

tags?:

string[]

Tags for grouping in Swagger UI. Defaults to ['custom'] if not specified.

deprecated?:

boolean

Mark the operation as deprecated

parameters?:

ParameterObject[]

Path, query, and header parameters

requestBody?:

RequestBodyObject

Request body specification

responses?:

ResponsesObject

Response specifications by status code

security?:

SecurityRequirementObject[]

Security requirements for the operation

Return value

Returns an ApiRoute object to be passed to server.apiRoutes in the Mastra configuration.

Handler context

The handler receives a Hono Context object with access to:

handler: async c => {
  // Get the Mastra instance
  const mastra = c.get('mastra')

  // Get request context
  const requestContext = c.get('requestContext')

  // Access path parameters
  const itemId = c.req.param('itemId')

  // Access query parameters
  const filter = c.req.query('filter')

  // Access request body
  const body = await c.req.json()

  // Return JSON response
  return c.json({ data: 'value' })
}

Examples

Basic GET Route

import { Mastra } from '@mastra/core'
import { registerApiRoute } from '@mastra/core/server'

export const mastra = new Mastra({
  server: {
    apiRoutes: [
      registerApiRoute('/health-check', {
        method: 'GET',
        handler: async c => {
          return c.json({ status: 'ok' })
        },
      }),
    ],
  },
})

Route with Path Parameters

registerApiRoute('/users/:userId/posts/:postId', {
  method: 'GET',
  handler: async c => {
    const userId = c.req.param('userId')
    const postId = c.req.param('postId')

    return c.json({ userId, postId })
  },
})

POST Route with Body

registerApiRoute('/items', {
  method: 'POST',
  handler: async c => {
    const body = await c.req.json()
    const mastra = c.get('mastra')

    // Process the request...

    return c.json({ id: 'new-id', ...body }, 201)
  },
})

Route with Middleware

registerApiRoute('/protected', {
  method: 'GET',
  middleware: [
    async (c, next) => {
      const token = c.req.header('Authorization')
      if (!token) {
        return c.json({ error: 'Unauthorized' }, 401)
      }
      await next()
    },
  ],
  handler: async c => {
    return c.json({ data: 'protected content' })
  },
})

Route with CORS

Use route-specific CORS when one custom route needs cross-origin credentials, but the rest of the server should keep the global CORS policy.

registerApiRoute('/customer-webhook', {
  method: 'POST',
  cors: {
    origin: ['https://customer-saas.example'],
    credentials: true,
  },
  handler: async c => {
    return c.json({ ok: true })
  },
})

Route with OpenAPI Documentation

import { z } from 'zod'

const ItemSchema = z.object({
  id: z.string(),
  name: z.string(),
  price: z.number(),
})

registerApiRoute('/items/:itemId', {
  method: 'GET',
  openapi: {
    summary: 'Get item by ID',
    description: 'Retrieves a single item by its unique identifier',
    tags: ['Items'],
    parameters: [
      {
        name: 'itemId',
        in: 'path',
        required: true,
        description: 'The item ID',
        schema: { type: 'string' },
      },
    ],
    responses: {
      200: {
        description: 'Item found',
        content: {
          'application/json': {
            schema: ItemSchema, // Zod schemas are converted to JSON Schema during OpenAPI generation
          },
        },
      },
      404: {
        description: 'Item not found',
      },
    },
  },
  handler: async c => {
    const itemId = c.req.param('itemId')
    return c.json({ id: itemId, name: 'Example', price: 9.99 })
  },
})

Using createHandler()

For routes that need async initialization:

registerApiRoute('/dynamic', {
  method: 'GET',
  createHandler: async c => {
    // Perform async setup
    const config = await loadConfig()

    return async c => {
      return c.json({ config })
    }
  },
})

Error handling

Throw errors with status codes using Hono's HTTPException:

import { HTTPException } from 'hono/http-exception'

registerApiRoute('/items/:itemId', {
  method: 'GET',
  handler: async c => {
    const itemId = c.req.param('itemId')
    const item = await findItem(itemId)

    if (!item) {
      throw new HTTPException(404, { message: 'Item not found' })
    }

    return c.json(item)
  },
})

Related

• Custom API Routes Guide: Usage guide with examples
• Server Middleware: Global middleware configuration
• createRoute(): Type-safe route creation for server adapters
• Server Routes: Built-in Mastra server routes