I developed Schmock for internal use, and I've been using it as a stand-in for our development backend for a year now.
It grew out of a practical need: frontend and integration work should not have to stop because a backend environment is unavailable, unstable, or still catching up. Schmock lets us point at an OpenAPI spec or define a few routes by hand, keep realistic state between requests, and carry on building.
Over time it became the kind of tool I wanted to share: quick to drop into a test or local app, predictable enough to rely on every day, and able to grow beyond the first happy-path demo. At its core, Schmock is a callable mock API with a plugin pipeline and adapters for the frameworks we use.
import { schmock } from '@schmock/core'
import { openapi } from '@schmock/openapi'
const mock = schmock({ state: {} })
mock.pipe(await openapi({
spec: './petstore.yaml',
seed: { pets: { count: 5 } }
}))
const res = await mock.handle('GET', '/pets')
// → { status: 200, body: [{ petId: 1, name: "Rex", ... }, ...] }After living with it in day-to-day development, these are the parts that have mattered most:
- OpenAPI-first: Point at a spec to register mock routes with stateful CRUD collections, seed data, security validation, and content negotiation
- Callable API: No HTTP server needed — call
mock.handle()directly in tests - Plugin pipeline: Chain plugins with
.pipe()for validation, pagination, filtering, or custom logic - Framework adapters: Use Express middleware, an Angular interceptor, or React and Vue fetch integration
- Smart data generation: Field-name-aware faker generates realistic data from schemas
- Consistent transports: Core, Fetch, Node HTTP, Express, Angular, and CLI share response validation, body suppression, and cancellation plumbing
| Package | Description |
|---|---|
@schmock/core |
Core mock builder, routing, and plugin pipeline |
@schmock/openapi |
Auto-register routes from OpenAPI/Swagger specs |
@schmock/faker |
Faker-powered automatic data generation |
@schmock/validation |
Request/response validation via AJV |
@schmock/query |
Pagination, sorting, and filtering |
@schmock/express |
Express middleware adapter |
@schmock/angular |
Angular HTTP interceptor adapter |
@schmock/react |
React provider, hook, and testing utilities |
@schmock/vue |
Vue plugin and composable |
@schmock/cli |
Standalone CLI mock server |
@schmock/schmock |
Aggregate package for Core, non-framework plugins, and CLI |
If you want to try it out, the smallest setup is just the core package:
npm install @schmock/coreconst mock = schmock()
mock('GET /users', [
{ id: 1, name: 'Alice' },
{ id: 2, name: 'Bob' },
])
mock('GET /users/:id', ({ params }) => {
const users = [{ id: 1, name: 'Alice' }, { id: 2, name: 'Bob' }]
return users.find(u => u.id === Number(params.id)) || [404, { error: 'Not found' }]
})
const res = await mock.handle('GET', '/users/1')
// → { status: 200, body: { id: 1, name: 'Alice' }, headers: {...} }const mock = schmock({ state: { items: [] } })
mock('POST /items', ({ body, state }) => {
const item = { id: state.items.length + 1, ...body }
state.items.push(item)
return [201, item]
})
mock('GET /items', ({ state }) => state.items)
await mock.handle('POST', '/items', { body: { name: 'Widget' } })
const list = await mock.handle('GET', '/items')
// list.body → [{ id: 1, name: 'Widget' }]import { openapi } from '@schmock/openapi'
const mock = schmock({ state: {} })
mock.pipe(await openapi({
spec: './petstore.yaml',
seed: { pets: [{ petId: 1, name: 'Rex', tag: 'dog' }] },
security: true,
}))
await mock.handle('GET', '/pets') // list
await mock.handle('GET', '/pets/1') // get by id
await mock.handle('POST', '/pets', { // create
body: { name: 'Buddy', tag: 'dog' },
headers: { authorization: 'Bearer token' },
})
await mock.handle('DELETE', '/pets/1') // deleteawait mock.handle('POST', '/items', { body: { name: 'A' } })
await mock.handle('POST', '/items', { body: { name: 'B' } })
mock.called('POST', '/items') // true
mock.callCount('POST', '/items') // 2
mock.lastRequest('POST', '/items') // { body: { name: 'B' }, ... }import { validationPlugin } from '@schmock/validation'
import { queryPlugin } from '@schmock/query'
mock('GET /users', ({ state }) => state.users)
.pipe(validationPlugin({ request: { query: querySchema } }))
.pipe(queryPlugin({
pagination: { defaultLimit: 20 },
sorting: { allowed: ['name', 'created_at'] },
filtering: { allowed: ['role'] },
}))
// GET /users?filter[role]=admin&sort=name&page=2&limit=10Express:
import { toExpress } from '@schmock/express'
app.use('/api', toExpress(mock))Angular:
import { provideSchmockInterceptor } from '@schmock/angular'
providers: [provideSchmockInterceptor(mock, { baseUrl: '/api' })]npm install -g @schmock/cli
schmock petstore.yaml --port 8080 --cors --seed seed.json| Guide | Description |
|---|---|
| Getting Started | Installation, core concepts, first mock |
| OpenAPI | Auto-mocking, CRUD, seed data, Prefer header, security, schema patching |
| Testing | Unit tests, integration tests, Angular & Express testing patterns |
| Express Adapter | Express middleware setup and options |
| Angular Adapter | Angular interceptor, helpers, TestBed setup |
| React Adapter | Provider, hook, fetch interception, and testing helper |
| Vue Adapter | Plugin, composable, and fetch interception |
| CLI | Command-line mock server |
| Plugin Development | Writing custom plugins |
| API Reference | Complete type and method reference |
| Debug Mode | Request lifecycle logging |
Contributions, bug reports, and questions are welcome. See CONTRIBUTING.md for the development setup and workflow.
MIT