From emulate
Local drop-in API emulator for Vercel, GitHub, Google, Slack, Apple, Microsoft, and AWS. Use when the user needs to start emulated services, configure seed data, write tests against local APIs, set up CI without network access, or work with the emulate CLI or programmatic API. Triggers include "start the emulator", "emulate services", "mock API locally", "create emulator config", "test against local API", "npx emulate", or any task requiring local service emulation.
npx claudepluginhub pleaseai/claude-code-plugins --plugin emulateThis skill is limited to using the following tools:
Local drop-in replacement services for CI and no-network sandboxes. Fully stateful, production-fidelity API emulation, not mocks.
Generates seed configs for Vercel's emulate tool, enabling stateful API emulation of GitHub, Vercel, AWS, MongoDB Atlas, and OAuth providers for tests, CI, and offline development.
Emulates Vercel, GitHub, and Google APIs via stateful local HTTP servers for CI pipelines, no-network sandboxes, and testing with Vitest/Jest.
Designs realistic mock APIs simulating production behavior for development, testing, demos, frontend integration, third-party APIs, and contract validation.
Share bugs, ideas, or general feedback.
Local drop-in replacement services for CI and no-network sandboxes. Fully stateful, production-fidelity API emulation, not mocks.
npx emulate
All services start with sensible defaults:
| Service | Default Port |
|---|---|
| Vercel | 4000 |
| GitHub | 4001 |
| 4002 | |
| Slack | 4003 |
| Apple | 4004 |
| Microsoft | 4005 |
| AWS | 4006 |
# Start all services (zero-config)
emulate
# Start specific services
emulate --service vercel,github
# Custom base port (auto-increments per service)
emulate --port 3000
# Use a seed config file
emulate --seed config.yaml
# Generate a starter config
emulate init
# Generate config for a specific service
emulate init --service vercel
# List available services
emulate list
| Flag | Default | Description |
|---|---|---|
-p, --port | 4000 | Base port (auto-increments per service) |
-s, --service | all | Comma-separated services to enable |
--seed | auto-detect | Path to seed config (YAML or JSON) |
The port can also be set via EMULATE_PORT or PORT environment variables.
npm install emulate
Each call to createEmulator starts a single service:
import { createEmulator } from 'emulate'
const github = await createEmulator({ service: 'github', port: 4001 })
const vercel = await createEmulator({ service: 'vercel', port: 4002 })
github.url // 'http://localhost:4001'
vercel.url // 'http://localhost:4002'
await github.close()
await vercel.close()
| Option | Default | Description |
|---|---|---|
service | (required) | 'vercel', 'github', 'google', 'slack', 'apple', 'microsoft', or 'aws' |
port | 4000 | Port for the HTTP server |
seed | none | Inline seed data (same shape as YAML config) |
| Method | Description |
|---|---|
url | Base URL of the running server |
reset() | Wipe the store and replay seed data |
close() | Shut down the HTTP server, returns a Promise |
import { createEmulator, type Emulator } from 'emulate'
let github: Emulator
let vercel: Emulator
beforeAll(async () => {
;[github, vercel] = await Promise.all([
createEmulator({ service: 'github', port: 4001 }),
createEmulator({ service: 'vercel', port: 4002 }),
])
process.env.GITHUB_URL = github.url
process.env.VERCEL_URL = vercel.url
})
afterEach(() => { github.reset(); vercel.reset() })
afterAll(() => Promise.all([github.close(), vercel.close()]))
Configuration is optional. The CLI auto-detects config files in this order:
emulate.config.yaml / .ymlemulate.config.jsonservice-emulator.config.yaml / .ymlservice-emulator.config.jsonOr pass --seed <file> explicitly. Run emulate init to generate a starter file.
tokens:
my_token:
login: admin
scopes: [repo, user]
vercel:
users:
- username: developer
name: Developer
email: dev@example.com
teams:
- slug: my-team
name: My Team
projects:
- name: my-app
team: my-team
framework: nextjs
integrations:
- client_id: oac_abc123
client_secret: secret_abc123
name: My Vercel App
redirect_uris:
- http://localhost:3000/api/auth/callback/vercel
github:
users:
- login: octocat
name: The Octocat
email: octocat@github.com
orgs:
- login: my-org
name: My Organization
repos:
- owner: octocat
name: hello-world
language: JavaScript
auto_init: true
oauth_apps:
- client_id: Iv1.abc123
client_secret: secret_abc123
name: My Web App
redirect_uris:
- http://localhost:3000/api/auth/callback/github
google:
users:
- email: testuser@example.com
name: Test User
oauth_clients:
- client_id: my-client-id.apps.googleusercontent.com
client_secret: GOCSPX-secret
redirect_uris:
- http://localhost:3000/api/auth/callback/google
slack:
team:
name: My Workspace
domain: my-workspace
users:
- name: developer
real_name: Developer
email: dev@example.com
channels:
- name: general
topic: General discussion
bots:
- name: my-bot
oauth_apps:
- client_id: "12345.67890"
client_secret: example_client_secret
name: My Slack App
redirect_uris:
- http://localhost:3000/api/auth/callback/slack
apple:
users:
- email: testuser@icloud.com
name: Test User
oauth_clients:
- client_id: com.example.app
team_id: TEAM001
name: My Apple App
redirect_uris:
- http://localhost:3000/api/auth/callback/apple
microsoft:
users:
- email: testuser@outlook.com
name: Test User
oauth_clients:
- client_id: example-client-id
client_secret: example-client-secret
name: My Microsoft App
redirect_uris:
- http://localhost:3000/api/auth/callback/microsoft-entra-id
aws:
region: us-east-1
s3:
buckets:
- name: my-app-bucket
sqs:
queues:
- name: my-app-events
iam:
users:
- user_name: developer
create_access_key: true
roles:
- role_name: lambda-execution-role
Tokens map to users. Pass them as Authorization: Bearer <token> or Authorization: token <token>. When no tokens are configured, a default test_token_admin is created for the admin user.
Each service also has a fallback user. If no token is provided, requests authenticate as the first seeded user.
Set environment variables to override real service URLs:
VERCEL_EMULATOR_URL=http://localhost:4000
GITHUB_EMULATOR_URL=http://localhost:4001
GOOGLE_EMULATOR_URL=http://localhost:4002
SLACK_EMULATOR_URL=http://localhost:4003
APPLE_EMULATOR_URL=http://localhost:4004
MICROSOFT_EMULATOR_URL=http://localhost:4005
AWS_EMULATOR_URL=http://localhost:4006
Then use these in your app to construct API and OAuth URLs. See each service's skill for SDK-specific override instructions.
packages/
emulate/ # CLI entry point + programmatic API
@emulators/
core/ # HTTP server (Hono), Store, plugin interface, middleware
vercel/ # Vercel API service plugin
github/ # GitHub API service plugin
google/ # Google OAuth 2.0 / OIDC plugin
slack/ # Slack Web API, OAuth, incoming webhooks plugin
apple/ # Sign in with Apple / OIDC plugin
microsoft/ # Microsoft Entra ID OAuth 2.0 / OIDC plugin
aws/ # AWS S3, SQS, IAM, STS plugin
The core provides a generic Store with typed Collection<T> instances supporting CRUD, indexing, filtering, and pagination. Each service plugin registers routes on the shared Hono app and uses the store for state.