Hono adapter

The @mastra/hono package provides a server adapter for running Mastra with Hono. For general adapter concepts (constructor options, initialization flow, etc.), see Server Adapters.

Installation

Install the Hono adapter and Hono framework:

npm

npm install @mastra/hono@latest hono

pnpm

pnpm add @mastra/hono@latest hono

Yarn

yarn add @mastra/hono@latest hono

Bun

bun add @mastra/hono@latest hono

Usage example

server.ts

import { Hono } from 'hono'
import { HonoBindings, HonoVariables, MastraServer } from '@mastra/hono'
import { mastra } from './mastra'

const app = new Hono<{ Bindings: HonoBindings; Variables: HonoVariables }>()
const server = new MastraServer({ app, mastra })

await server.init()

export default app

Constructor parameters

app:

Hono

Hono app instance

mastra:

Mastra

Mastra instance

prefix?:

string

= ''

Route path prefix (e.g., /api/v2)

openapiPath?:

string

= ''

Path to serve OpenAPI spec (e.g., /openapi.json)

bodyLimitOptions?:

{ maxSize: number, onError: (err) => unknown }

Request body size limits

streamOptions?:

{ redact?: boolean }

= { redact: true }

Stream redaction config. When true, redacts sensitive data from streams.

customRouteAuthConfig?:

Map<string, boolean>

Per-route auth overrides. Keys are METHOD:PATH (e.g., GET:/api/health). Value false makes route public, true requires auth.

tools?:

Record<string, Tool>

Available tools for the server

taskStore?:

InMemoryTaskStore

Task store for A2A (Agent-to-Agent) operations

mcpOptions?:

MCPOptions

MCP transport options. Set serverless: true for stateless environments like Cloudflare Workers or Vercel Edge.

Adding custom routes

Add routes directly to the Hono app:

server.ts

import { Hono } from 'hono'
import { HonoBindings, HonoVariables, MastraServer } from '@mastra/hono'

const app = new Hono<{ Bindings: HonoBindings; Variables: HonoVariables }>()
const server = new MastraServer({ app, mastra })

// Before init - runs before Mastra middleware
app.get('/early-health', c => c.json({ status: 'ok' }))

await server.init()

// After init - has access to Mastra context
app.get('/custom', c => {
  const mastraInstance = c.get('mastra')
  return c.json({ agents: Object.keys(mastraInstance.listAgents()) })
})

tip

Routes added before init() run without Mastra context. Add routes after init() to access the Mastra instance and request context.

When you want Mastra-managed auth and route metadata such as requiresAuth, prefer registerApiRoute(). For raw Hono routes mounted directly on app, use createAuthMiddleware():

server.ts

import { Hono } from 'hono'
import { createAuthMiddleware, HonoBindings, HonoVariables, MastraServer } from '@mastra/hono'
import { mastra } from './mastra'

const app = new Hono<{ Bindings: HonoBindings; Variables: HonoVariables }>()
const server = new MastraServer({ app, mastra })

await server.init()

app.get('/custom/protected', createAuthMiddleware({ mastra }), c => {
  const user = c.get('requestContext').get('user')
  return c.json({ user })
})

app.get('/custom/public', createAuthMiddleware({ mastra, requiresAuth: false }), c => {
  return c.json({ ok: true })
})

Accessing context

In Hono middleware and route handlers, access Mastra context via c.get():

app.get('/custom', async c => {
  const mastra = c.get('mastra')
  const requestContext = c.get('requestContext')
  const abortSignal = c.get('abortSignal')

  const agent = mastra.getAgent('myAgent')
  return c.json({ agent: agent.name })
})

Available context keys:

Key	Description
mastra	Mastra instance
requestContext	Request context map
abortSignal	Request cancellation signal
tools	Available tools
taskStore	Task store for A2A operations
customRouteAuthConfig	Per-route auth overrides
user	Authenticated user (if auth configured)

Adding middleware

Add Hono middleware with app.use() before init() to run it on every request. Mastra context isn't available at that point:

server.ts

import { Hono } from 'hono'
import { HonoBindings, HonoVariables, MastraServer } from '@mastra/hono'

const app = new Hono<{ Bindings: HonoBindings; Variables: HonoVariables }>()

// Runs on every request, before Mastra context exists
app.use('*', async (c, next) => {
  console.log(`${c.req.method} ${c.req.url}`)
  await next()
})

const server = new MastraServer({ app, mastra })
await server.init()

Middleware added after init() never runs for Mastra's routes. Hono dispatches handlers in registration order, so middleware registered after the routes only applies to routes added later.

To run middleware with Mastra context on Mastra's routes, use server.middleware in the Mastra config. The adapter registers it during init(), after the context step and before any route. These handlers are skipped for routes declared public with requiresAuth: false, so they can't block endpoints such as the Studio sign-in routes:

src/mastra/index.ts

import { Mastra } from '@mastra/core'

export const mastra = new Mastra({
  server: {
    middleware: [
      async (c, next) => {
        c.get('requestContext').set('locale', c.req.header('accept-language') ?? 'en')
        await next()
      },
    ],
  },
})

Manual initialization

For custom middleware ordering, call each method separately instead of init(). See manual initialization for details.

Examples

• Hono Adapter: Basic Hono server setup

Related

• Server Adapters: Shared adapter concepts
• MastraServer Reference: Full API reference
• createRoute() Reference: Creating type-safe custom routes