oproxy is a new open-source MITM proxy designed for developers who need to intercept and analyze network traffic during testing. The tool handles HTTP, HTTPS, and SOCKS5 protocols, allowing inspection of requests, responses, headers, and bodies without modifying application code. Developers can capture live sessions, replay requests, and export data as HAR files or code snippets in multiple languages.

Built with Rust 1.85 and Node.js 22, oproxy runs locally or in Docker containers with persistent storage for certificates and session data. Key features include HTTPS interception after trusting the generated CA, traffic modification through rule sets, mock responses, DNS overrides, and throttling capabilities. The proxy also supports WebSocket frame metadata inspection and integrates an authenticated assistant powered by OpenAI-compatible models.

Practical applications span browser debugging, CLI testing, mobile app development, and API client validation. Users can route traffic to staging services, reproduce bandwidth-limited responses, or validate client behavior when requests are blocked or rewritten. The tool serves its management UI and API from the same listener, simplifying deployment.

With support for server-sent events, JWT and GraphQL metadata inspection, and upstream proxy chaining, oproxy fills a gap for developers seeking a lightweight, programmable traffic inspection tool. The MIT license and straightforward Docker setup make it accessible for immediate integration into development workflows.