dotnet/dev-proxy

What it solves

Dev Proxy is designed to help developers test how their applications handle non-ideal network conditions—such as API errors, throttling, and slow responses—without needing to modify the application's source code. It eliminates the need to write temporary simulation code that won't be shipped to production.

How it works

It operates as a command-line tool that intercepts network requests. Because it acts as a proxy, it can work across any programming language, framework, or API. It allows developers to simulate failures, stand up mock APIs, and specifically route OpenAI-compatible requests to local language models to test AI applications without consuming tokens.

Who it’s for

Developers building apps that rely on external APIs, including those building AI experiences that need to ensure reliability and failure handling for LLM responses.

Highlights

• Zero Code Changes: Test API failures and slow responses without changing a single line of app code.
• AI Testing Support: Route OpenAI-compatible requests to local LLMs and simulate LLM failures to save tokens.
• Cross-Platform: Works as a CLI tool on any platform.
• CI/CD Integration: Can be automated via GitHub Actions for resilience testing.
• AI Agent Configuration: Supports configuration via an MCP server for use with AI coding agents.