Most localhost tunnels expose your dev server to the internet and hope nobody guesses the URL. Tunn lets you specify exactly who gets access.

tunn 8080 --allow=alice@gmail.com

Alice gets a link, logs in with GitHub or a magic link, and sees your localhost. Everyone else gets access denied.

- Works through corporate firewalls (it's just HTTPS)

- Free tier: 100MB/month, 3 tunnels

- Fully open source, self-hostable

Install: curl -fsSL https://tunn.to/install.sh | sh

GitHub: https://github.com/ehrlich-b/tunn

tunn.to is the hosted version, but it's fully self-hostable if you'd rather not trust some guy on the internet. This is a side project, not a startup - first thing I've shipped for myself.