List of free local-server stuff for developerππ½
If you're looking for all programming tools around local-server (not just free). Check this page List of local-server Programming Tools

ngrok
ngrok is the fastest way to put anything on the internet with a single command.
Tag: proxy, local-server, tunnel
Ephemeral/Random Domains Serve HTTP Apps, Webhooks, APIs, and TCP-based systems Automated SSL/TLS certificates Request Inspection & Replay APIs and Terraform Provider Restricted bandwidth and usage
Localtunnel
Free local server to public internet tunnel. Ngrok alternative. Expose yourself to the world
Tag: proxy, local-server, tunnel

Loophole
Instant hosting, right from your local machine. It's totally free and excellent alternative to ngrok
Tag: proxy, local-server, tunnel