Support `*.localhost` URLs as an alternative to external tunnel services

[2chanhaeng]

The fedify tunnel command currently relies on external tunneling services (localhost.run, serveo.net, pinggy.io). These services can be intermittently unavailable or rate-limited, causing tunnel failures during local development.

For purely local development and testing scenarios, we could support *.localhost URLs instead. Per RFC 6761, *.localhost subdomains resolve to 127.0.0.1 without any external dependency.

portless is a lightweight tool that replaces port numbers with stable, named .localhost URLs. It provides:

• Automatic HTTPS with HTTP/2 via a local CA
• Stable named URLs (e.g., https://myapp.localhost instead of http://localhost:3000)
• No dependency on external services
• Subdomain support (e.g., https://api.myapp.localhost)
• Cross-platform support (macOS, Linux, Windows)

Proposal

Add a --local (or similar) option to fedify tunnel and related commands (fedify inbox, fedify lookup, fedify relay) that uses portless to assign a *.localhost URL to the local server instead of opening an external tunnel.

Example usage:

fedify tunnel 3000 --local        # -> https://fedify.localhost (no external tunnel)
fedify tunnel 3000 -s serveo.net  # -> existing behavior via external service

Benefits

• Reliability: No dependency on third-party tunnel service availability
• Speed: No network round-trip through an external proxy
• Privacy: Traffic stays entirely on the local machine
• Simplicity: Works offline with no account or API key required

Limitations

• Only useful when both the client and server are on the same machine (or LAN with portless's --lan mode). External tunnel services are still needed for testing with remote fediverse instances.

Related

• portless (Apache-2.0, Node.js 20+)