--- title: Our Stack layout: docs sitemap: false toc: false nav: devjobs --- Our platform, the stuff that actually runs apps for our customers, is built on Rust and Go. Developers on all of our platform teams switch-hit between those two languages. We love them both, and that's an attribute we're looking for in platform devs. When a user aims their browser at an app hosted on Fly.io, they're talking to `fly-proxy`, a Rust / Tokio / Hyper proxy that powers our Anycast network. `fly-proxy` uses `attache`, our Go SQLite Consul cache, and `corrosion`, our Rust SWIM-based state replication service, to route requests to the right worker and VM. Those VMs were booted up by `flyd`, our Go orchestrator. Persistent encrypted storage for the VMs was provisioned by `vold`, another orchestration component. `flyd` leverages the Go-based `containerd` ecosystem to convert Docker containers into root filesystems for our VMs. The VMs themselves run under `firecracker`, Amazon's Rust-based hypervisor (and the engine behind Lambda and Fargate). Our hardware! Amazon's hypervisor code. Inside the VM, our code gets control again: we own the `init` that spins things up in the VM. `init` is Rust. More and more of our fun VM tricks are features of our `init`. To tell us what containers to boot up, our customers talk to our GraphQL API. The backend for that API is a Rails app, running on Postgres. Most of our developer UX happens in `flyctl`, our Go-based CLI. We're a CLI-first company. Fancy customer UI stuff? Elixir! We love Elixir and sponsor the Phoenix project. Generally, new UI stuff at Fly.io happens in Elixir/Phoenix/LiveView. LiveView screams on Fly.io.