Scalar Mock Server

A powerful Node.js mock server that automatically generates realistic API responses from your OpenAPI/Swagger documents. It creates fully-functional endpoints with mock data, handles authentication, and respects content types - making it perfect for frontend development, API prototyping, and integration testing.

Features

• Perfect for frontend development and testing
• Creates endpoints automatically from OpenAPI documents
• Generates realistic mock data based on your schemas
• Handles authentication and responds with defined HTTP headers
• Supports Swagger 2.0 and OpenAPI 3.x documents
• Customizable response handling

Quickstart

The easiest way to get started is through our Scalar CLI. You can have a mock server up and running in seconds:

npx @scalar/cli mock openapi.json --watch

Installation

For advanced use cases, you can integrate the mock server directly into your Node.js application for full control:

npm install @scalar/mock-server

Usage

import { serve } from '@hono/node-server'
import { createMockServer } from '@scalar/mock-server'

// Your OpenAPI document
const specification = {
  openapi: '3.1.1',
  info: {
    title: 'Hello World',
    version: '1.0.0',
  },
  paths: {
    '/foobar': {
      get: {
        responses: {
          '200': {
            description: 'OK',
            content: {
              'application/json': {
                example: {
                  foo: 'bar',
                },
              },
            },
          },
        },
      },
    },
  },
}

// Create the mocked routes
const app = await createMockServer({
  specification,
  // Custom logging
  onRequest({ context, operation }) {
    console.log(context.req.method, context.req.path)
  },
})

// Start the server
serve(
  {
    fetch: app.fetch,
    port: 3000,
  },
  (info) => {
    console.log(`Listening on http://localhost:${info.port}`)
  },
)

Authentication

You can define security schemes in your OpenAPI document and the mock server will validate the authentication:

import { serve } from '@hono/node-server'
import { createMockServer } from '@scalar/mock-server'

// Your OpenAPI document
const specification = {
  openapi: '3.1.1',
  info: {
    title: 'Hello World',
    version: '1.0.0',
  },
  paths: {
    '/secret': {
      get: {
        security: [
          {
            bearerAuth: [],
          },
          {
            apiKey: [],
          },
        ],
        responses: {
          '200': {
            description: 'OK',
            content: {
              'application/json': {
                example: {
                  foo: 'bar',
                },
              },
            },
          },
          '401': {
            description: 'Unauthorized',
            content: {
              'application/json': {
                example: {
                  error: 'Unauthorized',
                },
              },
            },
          },
        },
      },
    },
  },
  components: {
    securitySchemes: {
      bearerAuth: {
        type: 'http',
        scheme: 'bearer',
        bearerFormat: 'JWT',
      },
      apiKey: {
        type: 'apiKey',
        in: 'header',
        name: 'X-API-Key',
      },
    },
  },
}

// Create the mocked routes
const app = await createMockServer({
  specification,
  // Custom logging
  onRequest({ context, operation }) {
    console.log(context.req.method, context.req.path)
  },
})

// Start the server
serve(
  {
    fetch: app.fetch,
    port: 3000,
  },
  (info) => {
    console.log(`Listening on http://localhost:${info.port}`)
  },
)

OpenAPI endpoints

The given OpenAPI document is automatically exposed:

• /openapi.json and /openapi.yaml

Community

We are API nerds. You too? Let’s chat on Discord: https://discord.gg/scalar

License

The source code in this repository is licensed under MIT.