Fly.io | What It Is & How I Use It

Fly.io is an application hosting platform that runs full-stack apps close to users by deploying them as micro-VMs on hardware distributed across data centers worldwide. Unlike traditional serverless platforms that abstract away the server entirely, Fly.io gives you actual virtual machines powered by Firecracker, the same microVM technology that runs AWS Lambda. This means you can run any language, any framework, any process that works on Linux. For custom web application development, Fly.io is ideal when an app needs persistent connections, WebSockets, or co-located databases. You can run a PostgreSQL instance alongside your app in the same region, which eliminates the cross-network latency that plagues serverless database architectures. Deployment is Docker-based, you provide a Dockerfile or let Fly's buildpacks detect your stack, and the platform handles the rest. It also supports multi-region deployment, so your app can run simultaneously in Dallas, Amsterdam, and Tokyo.

01. Before It Existed

Fly.io was founded by Kurt Mackey and Jerome Gravel-Niquet in 2017. Mackey had previously co-founded Ars Technica, the influential technology publication, back in 1998 and served as its CEO for years. The original vision for Fly.io was actually an edge-based application proxy, a smart routing layer for existing apps. Over time, the company pivoted toward becoming a full application platform after realizing developers wanted to run their entire applications at the edge, not just route traffic to them. The breakthrough came with their adoption of Firecracker microVMs, which allowed them to boot full Linux environments in under 100 milliseconds and run them securely alongside other tenants.

02. What Makes It Different

Fly.io's co-founder Kurt Mackey built Ars Technica while he was still a college student, and it grew into one of the most respected technology publications in the world before being acquired by Conde Nast in 2008. His path from media founder to infrastructure CEO is one of the more unusual career arcs in tech. Additionally, Fly.io made headlines in the developer community for their unusually transparent engineering blog posts that openly discuss production incidents, architectural mistakes, and financial challenges, a level of candor rarely seen from hosting companies.