Show HN: BranchBox – isolated dev environments per feature (opens in new tab)

I built a small tool called BranchBox to solve a problem I kept running into while working with multiple coding agents and multiple features at the same time.

Parallel development sounds great until containers share ports, worktrees drift, databases collide, and environment variables leak across branches. My laptop would regularly get into broken states, and I wanted a predictable way to run several fully isolated environments side-by-side.

BranchBox creates a complete, self-contained dev environment for every feature:

• its own Git worktree

• its own devcontainer

• its own Docker network

• its own database

• its own ports

• its own environment variables

• optional tunnels (cloudflared for now, ngrok to come)

• shared credentials mounted safely

It is not a sandbox. It spins up real containers and real databases, but keeps everything isolated so nothing touches anything else unless you explicitly want it to. This has made parallel work (both human and agent-driven) much safer and more manageable.

I use it daily across several projects and wanted to share it in case others run into similar issues.

Repo: https://github.com/branchbox/branchbox Docs: https://branchbox.github.io/branchbox/

Happy to answer questions, share internals, or get feedback.