Mock APIs Across Protocols. Test Faster. Ship Better.

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What is Mokapi?

Mokapi is an open-source API mocking tool that lets you develop and test without waiting for backends. Mock REST APIs, Kafka topics, LDAP directories, and SMTP servers using OpenAPI and AsyncAPI specifications.

Perfect for:

• Frontend developers building UIs before backends exist
• QA teams testing edge cases, errors, and timeouts
• DevOps engineers running reliable CI/CD tests without external dependencies
• API designers prototyping and validating contracts early

Quick Start

Try Instantly

npx go-mokapi https://petstore3.swagger.io/api/v3/openapi.json

Then test your mock:

curl http://localhost/api/v3/pet/1 -H 'Accept: application/json'

Key Features

Multi-Protocol Support

Mock HTTP/HTTPS, Apache Kafka, LDAP, and SMTP — all from a single tool.

Specification-Driven

Uses OpenAPI and AsyncAPI specs as the source of truth. Your mocks stay aligned with your API contracts.

Dynamic Behavior with JavaScript

Control responses, simulate errors, add delays, or create complex workflows using embedded JavaScript:

import { on } from 'mokapi'

export default function() {
    on('http', (request, response) => {
        // Return 404 for specific IDs
        if (request.path.petId === '999') {
            response.statusCode = 404
            return
        }

        // Customize response data
        response.data.name = 'Custom Pet Name'
    })
}

Everything as Code

Version control your mocks alongside your code. Run them in CI/CD pipelines. No UI configuration required.

Configuration Patching

Override parts of your OpenAPI spec without modifying the original file. Perfect for testing different scenarios.

Built-in Dashboard

Visualize requests, responses, and logs in real-time at http://localhost:8080

Multiple Providers

Load specs from local files, HTTP URLs, Git repositories, or NPM packages.

Common Use Cases

Frontend Development

Mock backend APIs while building UIs. Test loading states, errors, and edge cases without waiting for real endpoints.

API Testing

Simulate timeouts, 500 errors, rate limits, and malformed responses. Test how your application handles failures.

CI/CD Integration

Run fast, reliable tests without external dependencies. No flaky tests due to network issues or unavailable services.

Contract Validation

Validate that your requests and responses match your OpenAPI specification. Catch breaking changes early.

Example Tutorials

Explore tutorials that walk you through mocking different protocols and scenarios:

• Get started with REST API
  Mock a REST API using OpenAPI specification

• Mock Kafka with AsyncAPI
  Simulate Kafka topics and validate message producers

• Mock LDAP Authentication
  Test authentication flows without a real LDAP server

• Mock SMTP Mail Servers
  Test email workflows without sending real messages

• CI/CD Integration with GitHub Actions
  Run Mokapi in automated test pipelines

More examples mokapi.io/resources

Documentation

• Getting Started Guide
• HTTP/REST API Documentation
• Kafka Documentation
• LDAP Documentation
• SMTP/Mail Documentation
• JavaScript API Reference
• Configuration Guide

Support the Project

If Mokapi helps your team ship faster, consider supporting development:

License

MIT License - see LICENSE for details.

Links

• Website: mokapi.io
• GitHub: github.com/marle3003/mokapi
• NPM Package: npmjs.com/package/go-mokapi
• Documentation: mokapi.io/docs
• Tutorials: mokapi.io/resources/tutorials
• Blog: mokapi.io/resources/blogs