Fly.io - Deploy Your Apps Everywhere Without the AWS Headache

Fly.io takes your Docker containers and runs them all over the world instead of making everyone hit some single server in Virginia like a caveman. They've got 35+ regions from Frankfurt to Sydney to wherever else you need, so your users don't have to deal with 300ms ping times because you cheaped out on infrastructure.

Uses the same Firecracker tech as Lambda but actually boots fast instead of making you wait 30 seconds for AWS to get its act together. Each "Fly Machine" is a dedicated microVM with actual guaranteed resources, not some shared container that dies when someone else's cryptocurrency trading bot starts hammering the CPU.

The Three Main Pieces

Fly Machines: Your containers run on these VMs. They start fast and scale from zero when traffic hits. The CLI doesn't make you want to throw your laptop, which is shocking after AWS trained us to expect every command-line tool to be complete shit.

Fly Proxy: Routes requests to the closest instance of your app. Works well until their infrastructure has a stroke and suddenly your traffic gets routed through the wrong continent.

WireGuard Mesh: All your apps talk to each other through an encrypted private network. No VPN bullshit to configure, which saves you from AWS VPC hell.

Companies like Supabase and Tailscale use it for production stuff, but the platform had some serious growing pains in 2023 when they got flooded with Heroku refugees after the free tier shutdown. Their CEO literally posted "reliability: it's not great" which was refreshingly honest but terrifying for production workloads.

Latest Drama (January 2025): Fly rolled out new CPU quota enforcement that throttles shared CPUs to 1/16th of a core, breaking deploys for Django, Rails, and Node.js apps that were working fine before. Users reported 8-minute deploy times instead of 30 seconds, with zero email notification about the breaking change. Classic Fly communication.

What Makes It Different

Global by Default: Your app just runs everywhere without you having to architect for multi-region deployment hell. No load balancers to configure or Route 53 DNS gymnastics to manage.

Persistent Storage Everywhere: Unlike pure serverless platforms, you can have actual disk storage that follows your app around. Useful for databases that don't fit in memory or when you need SQLite with your app.

Managed Postgres: They'll run PostgreSQL 17 for you with automatic backups and replication. Beats setting up your own Postgres clustering, though you're trusting a platform that's newer than your favorite pair of jeans with your production data.

The catch? There's no real free tier anymore - they just waive bills under $5/month since October 2024. Your hobby project might stay under $5 if you're careful, but don't expect to run anything with actual users without paying.

Look, the pricing gets complicated fast. Started with a $3 bill for a demo app, then hit $47 when I forgot to set autostop during a load test, now sitting around $28/month for a real app with actual users. They waive bills under $5/month since the October 2024 pricing changes, but don't call it "free" - it's more like "we can't be bothered sending invoices for coffee money."

Compute Costs (Per Second Billing)

Fly Machines charge per second of actual usage as of September 2025:

• shared-cpu-1x (256MB RAM): $0.0027/hour ($2/month running 24/7) - good for hobby projects
• performance-1x (2GB RAM): $0.01/hour ($7/month running 24/7) - where most real apps land
• performance-2x (4GB RAM): $0.02/hour ($14/month running 24/7) - for when your React app eats memory

The autostop feature can save you money by shutting down idle apps, but it adds 250ms+ cold start time to the first request after sleeping. Fine for hobby projects, annoying for anything users actually expect to work instantly.

The Surprise Costs

Bandwidth: $0.02/GB for North America/Europe egress, up to $0.12/GB for other regions. You bet your ass you'll get hit with surprise bills. Got nailed with a $340 bill when a bot started hammering our API endpoints and I forgot bandwidth costs actual money.

Persistent Volumes: $0.15/GB/month for SSD storage. Not terrible until you realize your 100GB database backup costs $15/month just sitting there.

Support Plans: Community support is forum-only where you'll spend 2 hours finding out your problem is a "known issue" that's been "on the roadmap" for 8 months. Paid support starts at $29/month, which feels steep when you're already paying $50+ for hosting.

What You'll Actually Pay

Hobby Project: If your app sleeps when idle and doesn't serve much bandwidth, probably stays under $5/month (waived). Set autostop or get ready for surprise bills.

Real Application: Budget $50-100/month minimum once you have real users and traffic. The per-second billing means costs scale with usage - sounds fair until your marketing team runs a campaign without warning you.

Production Workload: With multiple regions, monitoring, and decent storage, expect $200-500+/month. I've seen bills hit $800+ for a moderately busy app serving images.

Usage-based pricing sounds awesome until you get a $200 bill because some crawler decided to download every image on your site. The billing dashboard shows costs in real-time, which is either helpful monitoring or anxiety-inducing depending on your traffic patterns.

Language Support

Fly.io runs Docker containers, so anything that containerizes will work. But some frameworks get the VIP treatment:

VIP Treatment: Rails, Phoenix/Elixir, Django - they have dedicated deployment guides and actually work
Works Fine: Go, Rust, Python, Node.js - standard Docker deployment, no surprises
Probably Works: Everything else, but you're debugging Dockerfile issues at 3am when fly launch generates something that doesn't work

`fly launch` is genuinely helpful - it detects your framework and generates a working Dockerfile about 80% of the time according to their docs. When it works, it's magic. When it doesn't, you're back to editing Docker configs like everyone else, except now you're also learning fly.toml syntax.

Pro tip: Make sure you're running the latest flyctl - as of September 2025, that's v0.3.172 which fixed some annoying deployment edge cases. The CLI auto-updates but sometimes gets stuck, leaving you debugging issues that were already fixed.

Bottom line: Fly.io works well for many use cases, but expect to pay more than you initially budget and be ready for occasional reliability hiccups. The platform is solid for global deployment, just don't expect Heroku-level stability or AWS-level documentation.