Mock Server

A fake server that simulates API responses for testing and development purposes.

A mock server is a simulated server that mimics the behavior of a real API. It allows developers to test their applications without relying on actual backend services.

Why Use a Mock Server?

Parallel Development: Frontend teams can work independently while backend is being built
Reliable Testing: Get consistent responses without network issues or rate limits
Cost Savings: Avoid charges from third-party APIs during development
Edge Case Testing: Easily simulate errors, timeouts, and unusual scenarios

Popular Mock Server Tools

JSON Server - Quick REST API from a JSON file
MSW - Mock Service Worker for browser and Node.js
WireMock - Enterprise-grade mocking for Java
Mockoon - Desktop app with GUI
Prism - Auto-generate mocks from OpenAPI specs

Code Examples

JSON Server Setup

npx json-server --watch db.json --port 3001

Express Mock Server

const express = require("express");
const app = express();

app.get("/api/users/:id", (req, res) => {
  res.json({ id: req.params.id, name: "John Doe" });
});

app.listen(3001);

Related Terms

API Mocking

Simulating API behavior to enable development and testing without real backend services.

WebSocket

A protocol enabling full-duplex, real-time communication between client and server.

HTTP Status Codes

Standard response codes that indicate the result of an HTTP request.

Latency

The time delay between a request being sent and a response being received.