Hono adapter

The @mastra/hono package provides a server adapter for running Mastra with Hono.

info

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 before or after init():

server.ts

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

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

// Middleware before init
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 after init has access to Mastra context
app.use('*', async (c, next) => {
  const mastra = c.get('mastra')
  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