Mockoon

beginner

API mocking tool for development.

Overview

Mockoon is an open-source API mocking tool that enables developers to create realistic mock APIs without writing code. Originally launched as a desktop application, Mockoon has evolved to include a powerful CLI version that can simulate REST APIs with advanced features like templating, response rules, and request proxying. The tool generates HTTP responses based on predefined configurations, making it invaluable for frontend development, API testing, and service integration scenarios. This Docker configuration leverages Mockoon CLI to provide containerized API mocking capabilities that can be easily integrated into development workflows and CI/CD pipelines. The setup mounts local JSON configuration files that define API endpoints, responses, and behaviors, allowing teams to version control their mock definitions alongside application code. The containerized approach ensures consistent mock API behavior across different development environments while eliminating the need for developers to install and configure Mockoon locally. Development teams benefit from this stack when they need to develop against APIs that are still under development, test error conditions, or simulate third-party services without depending on external systems.

Key Features

JSON-based configuration system that supports version control and team collaboration
Built-in templating engine with Handlebars support for dynamic response generation
Advanced routing with wildcard patterns and parameter extraction from URLs
Response delay simulation to test application behavior under network latency conditions
Request/response logging and monitoring for debugging API interactions
OpenAPI specification import for rapid mock API creation from existing documentation
Proxy mode functionality to forward requests to real APIs while intercepting specific endpoints
CORS headers configuration for cross-origin request testing in browser applications

Common Use Cases

1Frontend development teams building applications before backend APIs are complete
2QA engineers testing application error handling by simulating API failures and edge cases
3Integration testing environments where third-party APIs need to be mocked for reliability
4Development workshops and training sessions requiring consistent API responses
5Microservices development where dependent services need to be simulated during testing
6Mobile app development requiring offline API simulation during device testing
7API contract testing to validate client applications against predefined API specifications

Prerequisites

Docker Engine 20.10+ and Docker Compose V2 for container orchestration
Minimum 512MB RAM allocation for Mockoon CLI container operations
Port 3000 available on host system or alternative port configuration knowledge
Basic understanding of REST API concepts and JSON structure for configuration
Mockoon desktop application for creating and exporting API configurations (optional but recommended)
Familiarity with OpenAPI/Swagger specifications if importing existing API documentation

For development & testing. Review security settings, change default credentials, and test thoroughly before production use. See Terms

docker-compose.yml

1services: 
2  mockoon: 
3    image: mockoon/cli:latest
4    container_name: mockoon
5    restart: unless-stopped
6    command: --data /data/api.json
7    volumes: 
8      - ./mockoon:/data
9    ports: 
10      - "3000:3000"

.env Template

.env

1# Create mockoon/api.json with your mock API

Usage Notes

1Docs: https://mockoon.com/docs/latest/about/
2Create API in Mockoon desktop app, export as JSON
3Mount exported JSON at /data/api.json
4API available at http://localhost:3000 (configurable)
5Supports templating, rules, proxying, and delays
6OpenAPI import supported for quick mock creation

Quick Start

terminal

1# 1. Create the compose file
2cat > docker-compose.yml << 'EOF'
3services:
4  mockoon:
5    image: mockoon/cli:latest
6    container_name: mockoon
7    restart: unless-stopped
8    command: --data /data/api.json
9    volumes:
10      - ./mockoon:/data
11    ports:
12      - "3000:3000"
13EOF
14
15# 2. Create the .env file
16cat > .env << 'EOF'
17# Create mockoon/api.json with your mock API
18EOF
19
20# 3. Start the services
21docker compose up -d
22
23# 4. View logs
24docker compose logs -f

One-Liner

Run this command to download and set up the recipe in one step:

terminal

1curl -fsSL https://docker.recipes/api/recipes/mockoon/run | bash

Troubleshooting

Container exits with 'ENOENT: no such file or directory' error: Ensure the mockoon directory exists and contains a valid api.json configuration file
API endpoints return 404 for all requests: Verify the JSON configuration file contains properly defined routes and the file is correctly mounted at /data/api.json
Port binding fails with 'port already in use' error: Change the host port in the ports mapping or stop conflicting services using port 3000
Mock API responses don't match expected format: Validate JSON configuration syntax and ensure Handlebars templating expressions are properly escaped
Container starts but API is unreachable: Check that the Mockoon configuration specifies the correct port (3000) and host binding (0.0.0.0) for container access

Community Notes

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Components

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