Fly.io review 2026: see how Firecracker microVMs, global Anycast networking, and usage-based pricing compare to Render, Railway, Heroku, and Vercel.
Fly.io is a developer-focused public cloud founded in 2017 by Kurt Mackey, Jerome Gravel-Niquet, and Michael Dwan, headquartered in Chicago, Illinois. Rather than hosting an application in one central region, Fly.io runs it as one or more Firecracker microVMs spread across a global network of physical servers, so requests are handled by the data center closest to the requesting user.
The platform has raised roughly 110.5 million dollars in venture funding, including a Series A led by Intel Capital, a Series B led by Andreessen Horowitz, and a 70 million dollar Series C led by EQT Ventures that valued the company at approximately 397 million dollars in 2023. That capital has largely gone toward acquiring and leasing bare-metal server capacity across dozens of cities worldwide.
Applications are packaged as container images and deployed as Fly Machines, described in a fly.toml file and managed through the flyctl command-line tool or the Fly Machines API. Traffic is routed with BGP Anycast networking and a custom Rust-based proxy called fly-proxy, which terminates TLS at the nearest data center and, when necessary, backhauls connections to another region over an encrypted WireGuard tunnel.
Beyond compute, Fly.io offers persistent Volumes for durable block storage, managed Fly Postgres for relational databases, a private WireGuard network by default for every organization, and a managed Fly Kubernetes offering, along with integrations for object storage and Redis-compatible caching through partner services.
Fly.io uses fully usage-based pricing: compute is billed per second based on the CPU and RAM preset of each Machine, storage is billed per gigabyte for Volumes and snapshots, and outbound data transfer is billed per gigabyte with rates that vary by region. Dedicated IPv4 addresses, extra SSL certificates, and Fly Kubernetes clusters carry additional flat monthly fees.
As of October 2024, Fly.io retired its legacy Hobby, Launch, and Scale plans that bundled a small free allowance of shared-cpu Machines and bandwidth. New accounts now receive only a short trial of about 2 VM hours or 7 days before pay-as-you-go billing with a credit card is required, after which billing is strictly pay-as-you-go, with optional paid support plans available for teams that need guaranteed response times.
Fly.io is used to deploy applications, APIs, and databases so they run physically close to end users in multiple regions, using Firecracker microVMs and a global Anycast network instead of a single centralized server.
Fly.io removed its free allowance plans (Hobby, Launch, and Scale) in October 2024. New accounts now get a short trial of about 2 VM hours or 7 days before pay-as-you-go billing with a credit card is required.
Fly.io bills per second for compute based on the CPU and memory preset of each Machine, per gigabyte for storage Volumes and snapshots, and per gigabyte for outbound data transfer, with additional flat fees for items like dedicated IPv4 addresses and Fly Kubernetes clusters.
Fly.io was founded in 2017 by Kurt Mackey, Jerome Gravel-Niquet, and Michael Dwan, and is headquartered in Chicago, Illinois.
Fly.io runs customer applications in Firecracker microVMs on physical servers distributed worldwide, using BGP Anycast routing, a Rust-based proxy called fly-proxy, and WireGuard tunnels to route traffic to the nearest available instance.
Fly.io emphasizes global multi-region deployment and low-level container control, while Render offers simpler fixed-price single-region hosting, Railway focuses on developer-experience simplicity with usage-based billing, Heroku is a legacy PaaS with a shrinking feature set, and Vercel specializes in frontend frameworks like Next.js rather than general backend and database hosting.