Initial problem
Every developer runs multiple projects locally and every project fights over the same ports. Port 3000, 8080, 5173 collide constantly. Developers waste time reconfiguring, killing zombie processes, and remembering which project runs where. Docker helps but adds overhead and complexity. There was no simple, fully native tool that gave each project its own identity on localhost.
Implementation
Loopbox assigns each project a dedicated loopback IP and stable hostnames like web.myproject.localhost. A lightweight reverse proxy handles host based HTTP routing, gRPC h2c and TCP passthrough with sub millisecond latency. A built in Agent API at 127.0.0.1:39393 lets AI coding assistants like Cursor, Claude, and Copilot discover, inspect, and control project sandboxes. Everything is declared in a single TOML config file, version controllable and reproducible across machines. Built entirely in Rust with a native macOS UI powered by Dioxus, using only around 120 MB of RAM.
Outcome
My contribution
Impact
What mattered
Dedicated loopback IP per project with zero port conflicts
Agent API enabling AI assistants to list projects, tail logs, and control services
Sub millisecond proxy latency with native macOS performance
Persistent process supervisor with crash detection and automatic restart
Traffic inspector for HTTP and gRPC request capture (Pro)
Single TOML config file for reproducible, version controllable setups
Insights
The main sandbox overview showing all managed projects with their services and status
Technical frame
The technical frame sits at the end on purpose: it shows the engineering substance behind the solution.
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