FastFN – Polyglot File-Based API Runtime

A modern take on CGI-style deployment that lets developers write APIs and SPAs using Python, Node, PHP, Lua, Rust, or Go in one project without complex frameworks. Simplifies mixed-language projects with straightforward file-to-route mapping and local dev experience.

The rise of edge runtimes and multi-language monorepos has created genuine frustration with per-language toolchains, and developers increasingly want "just run it" local dev experiences without Dockerizing everything — Deno Deploy and Vercel's edge functions have normalized polyglot-adjacent thinking but neither solves the mixed-runtime-in-one-project case cleanly. The closest incumbent is the original CGI model itself, which died for good reasons: performance, security, and operational complexity — and those same ghosts will haunt this. The $1k–4k/mo revenue band is realistic only if monetization targets teams or small agencies who'd pay for a hosted version, since individual developers rarely pay for dev tooling at all; the math gets thin fast. The most likely failure mode is that the target user — someone running Python, Lua, and Go in one project — is rare enough in practice that the addressable market is a curiosity, not a business.