The polyglot stack behind Fibe: Rails, a Rust core, a NestJS genie, and a Go SDK
· 21 min read
People assume four languages means four teams who couldn't agree, or four phases of a rewrite that never finished. Neither is true here. Fibe speaks Ruby, Rust, TypeScript, and Go on purpose, and each one is doing a job the others would do worse. The interesting part isn't the list — every grown-up system has a list. It's the rule that decides which language a given function lands in, and how boring we kept the seams between them.
This post is the honest version: what each piece is, why it exists, and the trade-offs we swallowed to get here. If you've ever stared at a monolith and wondered when to carve a piece off — and into what — this is one team's answer.