Vite DevTools Kit

Build custom developer tools that integrate with Vite DevTools using @vitejs/devtools-kit.

Core Concepts

A DevTools plugin extends a Vite plugin with a devtools.setup(ctx) hook. The context provides:

Property	Purpose
ctx.docks	Register dock entries (iframe, action, custom-render, launcher, json-render)
ctx.views	Host static files for UI
ctx.rpc	Register RPC functions, broadcast to clients
ctx.rpc.sharedState	Synchronized server-client state
ctx.logs	Emit structured log entries and toast notifications
ctx.terminals	Spawn and manage child processes with streaming terminal output
ctx.createJsonRenderer	Create server-side JSON render specs for zero-client-code UIs
ctx.commands	Register executable commands with keyboard shortcuts and palette visibility
ctx.viteConfig	Resolved Vite configuration
ctx.viteServer	Dev server instance (dev mode only)
ctx.mode	'dev' or 'build'

Quick Start: Minimal Plugin

/// <reference types="@vitejs/devtools-kit" />
import type { Plugin } from 'vite'

export default function myPlugin(): Plugin {
  return {
    name: 'my-plugin',
    devtools: {
      setup(ctx) {
        ctx.docks.register({
          id: 'my-plugin',
          title: 'My Plugin',
          icon: 'ph:puzzle-piece-duotone',
          type: 'iframe',
          url: 'https://example.com/devtools',
        })
      },
    },
  }
}

Quick Start: Full Integration

/// <reference types="@vitejs/devtools-kit" />
import type { Plugin } from 'vite'
import { fileURLToPath } from 'node:url'
import { defineRpcFunction } from '@vitejs/devtools-kit'

export default function myAnalyzer(): Plugin {
  const data = new Map<string, { size: number }>()

  return {
    name: 'my-analyzer',

    // Collect data in Vite hooks
    transform(code, id) {
      data.set(id, { size: code.length })
    },

    devtools: {
      setup(ctx) {
        // 1. Host static UI
        const clientPath = fileURLToPath(
          new URL('../dist/client', import.meta.url)
        )
        ctx.views.hostStatic('/.my-analyzer/', clientPath)

        // 2. Register dock entry
        ctx.docks.register({
          id: 'my-analyzer',
          title: 'Analyzer',
          icon: 'ph:chart-bar-duotone',
          type: 'iframe',
          url: '/.my-analyzer/',
        })

        // 3. Register RPC function
        ctx.rpc.register(
          defineRpcFunction({
            name: 'my-analyzer:get-data',
            type: 'query',
            setup: () => ({
              handler: async () => Array.from(data.entries()),
            }),
          })
        )
      },
    },
  }
}

Namespacing Convention

CRITICAL: Always prefix RPC functions, shared state keys, dock IDs, and command IDs with your plugin name:

// Good - namespaced
'my-plugin:get-modules'
'my-plugin:state'
'my-plugin:clear-cache'  // command ID

// Bad - may conflict
'get-modules'
'state'

Dock Entry Types

Type	Use Case
iframe	Full UI panels, dashboards (most common)
json-render	Server-side JSON specs — zero client code needed
action	Buttons that trigger client-side scripts (inspectors, toggles)
custom-render	Direct DOM access in panel (framework mounting)
launcher	Actionable setup cards for initialization tasks

Iframe Entry

ctx.docks.register({
  id: 'my-plugin',
  title: 'My Plugin',
  icon: 'ph:house-duotone',
  type: 'iframe',
  url: '/.my-plugin/',
})

Action Entry

ctx.docks.register({
  id: 'my-inspector',
  title: 'Inspector',
  icon: 'ph:cursor-duotone',
  type: 'action',
  action: {
    importFrom: 'my-plugin/devtools-action',
    importName: 'default',
  },
})

Custom Render Entry

ctx.docks.register({
  id: 'my-custom',
  title: 'Custom View',
  icon: 'ph:code-duotone',
  type: 'custom-render',
  renderer: {
    importFrom: 'my-plugin/devtools-renderer',
    importName: 'default',
  },
})

JSON Render Entry

Build UIs entirely from server-side TypeScript — no client code needed:

const ui = ctx.createJsonRenderer({
  root: 'root',
  elements: {
    root: {
      type: 'Stack',
      props: { direction: 'vertical', gap: 12 },
      children: ['heading', 'info'],
    },
    heading: {
      type: 'Text',
      props: { content: 'Hello from JSON!', variant: 'heading' },
    },
    info: {
      type: 'KeyValueTable',
      props: {
        entries: [
          { key: 'Version', value: '1.0.0' },
          { key: 'Status', value: 'Running' },
        ],
      },
    },
  },
})

ctx.docks.register({
  id: 'my-panel',
  title: 'My Panel',
  icon: 'ph:chart-bar-duotone',
  type: 'json-render',
  ui,
})

Launcher Entry

const entry = ctx.docks.register({
  id: 'my-setup',
  title: 'My Setup',
  icon: 'ph:rocket-launch-duotone',
  type: 'launcher',
  launcher: {
    title: 'Initialize My Plugin',
    description: 'Run initial setup before using the plugin',
    buttonStart: 'Start Setup',
    buttonLoading: 'Setting up...',
    onLaunch: async () => {
      // Run initialization logic
    },
  },
})

Terminals & Subprocesses

Spawn and manage child processes with streaming terminal output:

const session = await ctx.terminals.startChildProcess(
  {
    command: 'vite',
    args: ['build', '--watch'],
    cwd: process.cwd(),
  },
  {
    id: 'my-plugin:build-watcher',
    title: 'Build Watcher',
    icon: 'ph:terminal-duotone',
  },
)

// Lifecycle controls
await session.terminate()
await session.restart()

A common pattern is combining with launcher docks — see Terminals Patterns.

Commands & Command Palette

Register executable commands discoverable via Mod+K palette:

import { defineCommand } from '@vitejs/devtools-kit'

ctx.commands.register(defineCommand({
  id: 'my-plugin:clear-cache',
  title: 'Clear Build Cache',
  icon: 'ph:trash-duotone',
  keybindings: [{ key: 'Mod+Shift+C' }],
  when: 'clientType == embedded',
  handler: async () => { /* ... */ },
}))

Commands support sub-commands (two-level hierarchy), conditional visibility via when clauses, and user-customizable keyboard shortcuts.

See Commands Patterns and When Clauses for full details.

Logs & Notifications

Plugins can emit structured log entries from both server and client contexts. Logs appear in the built-in Logs panel and can optionally show as toast notifications.

Fire-and-Forget

// No await needed
context.logs.add({
  message: 'Plugin initialized',
  level: 'info',
})

With Handle

const handle = await context.logs.add({
  id: 'my-build',
  message: 'Building...',
  level: 'info',
  status: 'loading',
})

// Update later
await handle.update({
  message: 'Build complete',
  level: 'success',
  status: 'idle',
})

// Or dismiss
await handle.dismiss()

Key Fields

Field	Type	Description
message	string	Short title (required)
level	'info' | 'warn' | 'error' | 'success' | 'debug'	Severity (required)
description	string	Detailed description
notify	boolean	Show as toast notification
filePosition	{ file, line?, column? }	Source file location (clickable)
elementPosition	{ selector?, boundingBox?, description? }	DOM element position
id	string	Explicit id for deduplication
status	'loading' | 'idle'	Shows spinner when loading
category	string	Grouping (e.g., 'a11y', 'lint')
labels	string[]	Tags for filtering
autoDismiss	number	Toast auto-dismiss time in ms (default: 5000)
autoDelete	number	Auto-delete time in ms

The from field is automatically set to 'server' or 'browser'.

Deduplication

Re-adding with the same id updates the existing entry instead of creating a duplicate:

context.logs.add({ id: 'my-scan', message: 'Scanning...', level: 'info', status: 'loading' })
context.logs.add({ id: 'my-scan', message: 'Scan complete', level: 'success', status: 'idle' })

RPC Functions

Server-Side Definition

import { defineRpcFunction } from '@vitejs/devtools-kit'

const getModules = defineRpcFunction({
  name: 'my-plugin:get-modules',
  type: 'query', // 'query' | 'action' | 'static'
  setup: ctx => ({
    handler: async (filter?: string) => {
      // ctx has full DevToolsNodeContext
      return modules.filter(m => !filter || m.includes(filter))
    },
  }),
})

// Register in setup
ctx.rpc.register(getModules)

Client-Side Call (iframe)

import { getDevToolsRpcClient } from '@vitejs/devtools-kit/client'

const rpc = await getDevToolsRpcClient()
const modules = await rpc.call('my-plugin:get-modules', 'src/')

Client-Side Call (action/renderer script)

import type { DevToolsClientScriptContext } from '@vitejs/devtools-kit/client'

export default function setup(ctx: DevToolsClientScriptContext) {
  ctx.current.events.on('entry:activated', async () => {
    const data = await ctx.current.rpc.call('my-plugin:get-data')
  })
}

Client Context

The global client context (DevToolsClientContext) provides access to the RPC client and is set automatically when DevTools initializes (embedded or standalone). Use getDevToolsClientContext() to access it from anywhere on the client side:

import { getDevToolsClientContext } from '@vitejs/devtools-kit/client'

const ctx = getDevToolsClientContext()
if (ctx) {
  const modules = await ctx.rpc.call('my-plugin:get-modules')
}

Broadcasting to Clients

// Server broadcasts to all clients
ctx.rpc.broadcast({
  method: 'my-plugin:on-update',
  args: [{ changedFile: '/src/main.ts' }],
})

Type Safety

Extend the DevTools Kit interfaces for full type checking:

// src/types.ts
import '@vitejs/devtools-kit'

declare module '@vitejs/devtools-kit' {
  interface DevToolsRpcServerFunctions {
    'my-plugin:get-modules': (filter?: string) => Promise<Module[]>
  }

  interface DevToolsRpcClientFunctions {
    'my-plugin:on-update': (data: { changedFile: string }) => void
  }

  interface DevToolsRpcSharedStates {
    'my-plugin:state': MyPluginState
  }
}

Shared State

Server-Side

const state = await ctx.rpc.sharedState.get('my-plugin:state', {
  initialValue: { count: 0, items: [] },
})

// Read
console.log(state.value())

// Mutate (auto-syncs to clients)
state.mutate((draft) => {
  draft.count += 1
  draft.items.push('new item')
})

Client-Side

const client = await getDevToolsRpcClient()
const state = await client.rpc.sharedState.get('my-plugin:state')

// Read
console.log(state.value())

// Subscribe to changes
state.on('updated', (newState) => {
  console.log('State updated:', newState)
})

Client Scripts

For action buttons and custom renderers:

// src/devtools-action.ts
import type { DevToolsClientScriptContext } from '@vitejs/devtools-kit/client'

export default function setup(ctx: DevToolsClientScriptContext) {
  ctx.current.events.on('entry:activated', () => {
    console.log('Action activated')
    // Your inspector/tool logic here
  })

  ctx.current.events.on('entry:deactivated', () => {
    console.log('Action deactivated')
    // Cleanup
  })
}

Export from package.json:

{
  "exports": {
    ".": "./dist/index.mjs",
    "./devtools-action": "./dist/devtools-action.mjs"
  }
}

Debugging with Self-Inspect

Use @vitejs/devtools-self-inspect to debug your DevTools plugin. It shows registered RPC functions, dock entries, client scripts, and plugins in a meta-introspection UI at /.devtools-self-inspect/.

import DevTools from '@vitejs/devtools'
import DevToolsSelfInspect from '@vitejs/devtools-self-inspect'

export default defineConfig({
  plugins: [
    DevTools(),
    DevToolsSelfInspect(),
  ],
})

Best Practices

1. Always namespace - Prefix all identifiers with your plugin name
2. Use type augmentation - Extend DevToolsRpcServerFunctions for type-safe RPC
3. Keep state serializable - No functions or circular references in shared state
4. Batch mutations - Use single mutate() call for multiple changes
5. Host static files - Use ctx.views.hostStatic() for your UI assets
6. Use Iconify icons - Prefer ph:* (Phosphor) icons: icon: 'ph:chart-bar-duotone'
7. Deduplicate logs - Use explicit id for logs representing ongoing operations
8. Use Self-Inspect - Add @vitejs/devtools-self-inspect during development to debug your plugin
9. Namespace command IDs - Use my-plugin:action pattern for command IDs, same as RPC and state
10. Use when clauses - Conditionally show commands/docks with when expressions instead of programmatic show/hide

Example Plugins

Real-world example plugins in the repo — reference their code structure and patterns when building new integrations:

• A11y Checker (examples/plugin-a11y-checker) — Action dock entry, client-side axe-core audits, logs with severity levels and element positions, log handle updates
• File Explorer (examples/plugin-file-explorer) — Iframe dock entry, RPC functions (static/query/action), hosted UI panel, RPC dump for static builds, backend mode detection
• Git UI (examples/plugin-git-ui) — JSON render dock entry, server-side JSON specs, $bindState two-way binding, $state in action params, dynamic badge updates

Further Reading

• RPC Patterns - Advanced RPC patterns and type utilities
• Dock Entry Types - Detailed dock configuration options
• Shared State Patterns - Framework integration examples
• Project Structure - Recommended file organization
• JSON Render Patterns - Server-side JSON specs, components, state binding
• Terminals Patterns - Child processes, custom streams, session lifecycle
• Logs Patterns - Log entries, toast notifications, and handle patterns
• Commands Patterns - Command registration, sub-commands, keybindings, palette integration
• When Clauses - Conditional expression syntax, context variables, API reference