connexions

Connexions

Connexions is a mock server generator for OpenAPI specifications.
It allows you to define multiple APIs and generate meaningful mock responses automatically.
You can also define static responses for any arbitrary path.

Goals

• provide a simple tool to work with API mocks
• combine multiple APIs into one server
• generate meaningful responses

Features

• Multiple APIs on one server - each spec becomes a service with its own URL prefix
• Upstream proxy - forward to real backends with fallback to mocks
• Latency & error simulation - test how your app handles delays and failures
• Custom middleware - modify requests/responses on the fly
• Response caching - cache GET responses for consistency
• Request validation - validate against OpenAPI spec

Real-World Validation

Connexions continuously generates and validates data against 2,200+ real-world OpenAPI specifications from mockzilla/specs:

Total: 2215 services, 98464 endpoints
✅ Success: 98464  ❌ Fails: 0

Modes

Connexions runs in two modes:

• Portable - point at OpenAPI specs and run. No code generation, no setup.
• Codegen - generate typed Go handlers with custom logic and middleware.

Quick Start

Homebrew

brew tap mockzilla/tap
brew install connexions
connexions https://petstore3.swagger.io/api/v3/openapi.json

Go

go run github.com/mockzilla/connexions/v2/cmd/server@latest \
  https://petstore3.swagger.io/api/v3/openapi.json

Templates

• Portable template - embed specs into a single binary via go:embed
• Codegen template - generate Go handlers with custom logic and middleware

Read full documentation at mockzilla.github.io/connexions.

OpenAPI Specification

License

Copyright (c) 2023-present

Licensed under the MIT License