We’re Fly.io, a public cloud platform that is both our favorite way to put an app on the Internet and our favorite way to safely let a frontier agent coding harness cook. This is a post about our company, the future, and Sprites, which are computers for agents that you can check out right now. This ...

Building agents is fun. Rebuilding agents that break themselves… less so. A lot of Fly people are building agents with less of a penchant for self-destruction by teaching their agents to do anything risky in a Sprite. You get an agent that stays alive long enough to actually use its snazzy self-impr...

Sprites are disposable cloud computers. They appear instantly, always include durable filesystems, and cost practically nothing when idle. They’re the best and safest place on the Internet to run agents and we want you to create dozens of them. Sprites are a place to run agents; the first thing you ...

I’m Ben Johnson, and I work on Litestream at Fly.io. Litestream is the missing backup/restore system for SQLite. It’s free, open-source software that should run anywhere, and you can read more about it here. Each time we write about it, we get a little bit better at golfing down a description of wha...

We’re Fly.io, and this is the place in the post where we’d normally tell you that our job is to take your containers and run them on our own hardware all around the world. But last week, we launched Sprites, and they don’t work that way at all. Sprites are something new: Docker without Docker withou...

The state of the art in agent isolation is a read-only sandbox. At Fly.io, we’ve been selling that story for years, and we’re calling it: ephemeral sandboxes are obsolete. Stop killing your sandboxes every time you use them. My argument won’t make sense without showing you something new we’ve built....

I’m Ben Johnson, and I work on Litestream at Fly.io. Litestream is the missing backup/restore system for SQLite. It’s free, open-source software that should run anywhere, and you can read more about it here. Again with the sandwiches: assume we’ve got a SQLite database of sandwich ratings, and we’ve...

Some concepts are easy to grasp in the abstract. Boiling water: apply heat and wait. Others you really need to try. You only think you understand how a bicycle works, until you learn to ride one. There are big ideas in computing that are easy to get your head around. The AWS S3 API. It’s the most im...

Fly.io transmogrifies Docker containers into Fly Machines: micro-VMs running on our own hardware all over the world. The hardest part of running this platform isn’t managing the servers, and it isn’t operating the network; it’s gluing those two things together. Several times a second, as customer CI...

The $FLY Airdrop is live! Claim your share of the token powering Fly.io’s global network of 3M+ apps and (🤮) own a piece of the sky! We know. Our Twitter got owned. We knew within moments of it happening. We know exactly how it happened. Nothing was at risk other than our Twitter account (and one Fl...

I’m Ben Johnson, and I work on Litestream at Fly.io. Litestream makes it easy to build SQLite-backed full-stack applications with resilience to server failure. It’s open source, runs anywhere, and it’s easy to get started. Litestream is the missing backup/restore system for SQLite. It runs as a side...

I’m an audiophile, which is a nice way to describe someone who spends their children’s college fund on equipment that yields no audible improvement in sound quality. As such, I refused to use wireless headphones for the longest time. The fun thing about wired headphones is when you forget they’re on...

Trust calibration is a concept from the world of human-machine interaction design, one that is super relevant to AI software builders. Trust calibration is the practice of aligning the level of trust that users have in our products with its actual capabilities. If we build things that our users trus...

Recently, I suggested that The Future Isn’t Model Agnostic, that it’s better to pick one model that works for your project and build around it, rather than engineering for model flexibility. If you buy that, you also have to acknowledge how important comprehensive model evaluation becomes. Benchmark...

Your users don’t care that your AI project is model agnostic. In my last project, I spent countless hours ensuring that the LLMs running my services could be swapped out as easily as possible. I couldn’t touch a device with an internet connection without hearing about the latest benchmark-breaking m...

I’m Chris McCord, the creator of Elixir’s Phoenix framework. For the past several months, I’ve been working on a skunkworks project at Fly.io, and it’s time to show it off. I wanted LLM agents to work just as well with Elixir as they do with Python and JavaScript. Last December, in order to figure o...

With Fly.io, you can get your app running globally in a matter of minutes, and with MCP servers you can integrate with Claude, VSCode, Cursor and many more AI clients. Try it out for yourself! The introduction to Model Context Protocol starts out with: MCP is an open protocol that standardizes how a...

A heartfelt provocation about AI-assisted programming. Tech execs are mandating LLM adoption. That’s bad strategy. But I get where they’re coming from. Some of the smartest people I know share a bone-deep belief that AI is a fad — the next iteration of NFT mania. I’ve been reluctant to push back on ...

Agile Web Development with Rails 8 is off to production, where they do things like editing, indexing, pagination, and printing. In researching the chapter on Deployment and Production, I became very dissatisfied with the content available on Kamal. I ended up writing my own, and it went well beyond ...

We’re Fly.io, a public cloud that runs apps in a bunch of locations all over the world. This is a post about a gnarly bug in our Anycast router, the largest Rust project in our codebase. You won’t need much of any Rust to follow it. The basic idea is simple: customers give us Docker containers, and ...

Litestream is an open-source tool that makes it possible to run many kinds of full-stack applications on top of SQLite by making them reliably recoverable from object storage. This is a post about the biggest change we’ve made to it since I launched it. Nearly a decade ago, I got a bug up my ass. I ...

This is a blog post. Part showing off. Part opinion. Plan accordingly. The Model Context Protocol is days away from turning six months old. You read that right, six months old. MCP Servers have both taken the world by storm, and still trying to figure out what they want to be when they grow up. Ther...

Today’s state of the art is K8S, Terraform, web based UIs, and CLIs. Those days are numbered. On Monday, I created my first fly volume using an MCP. For those who don’t know what MCPs are, they are how you attach tools to LLMs like Claude or Cursor. I added support for fly volume create to fly mcp s...

I wrote this post on our internal message board, and then someone asked, “why is this an internal post and not on our blog”, so now it is. well, Cursor built I built the most basic MCP server for flyctl I could think of. It took 30 minutes. MCP, for those unaware, is the emerging standard protocol f...

We’re Fly.io, a developer-focused public cloud. We turn Docker containers into hardware-isolated virtual machines running on our own metal around the world. We spent years coming up with a developer experience we were proud of. But now the robots are taking over, and they don’t care. It’s weird to s...

We’re Fly.io, a security bearer token company with a public cloud problem. You can read more about what our platform does (Docker container goes in, virtual machine in Singapore comes out), but this is just an engineering deep-dive into how we make our security tokens work. It’s a tokens nerd post. ...

Here’s a fun bug. The basic idea of our service is that we run containers for our users, as hardware-isolated virtual machines (Fly Machines), on hardware we own around the world. What makes that interesting is that we also connect every Fly Machine to a global Anycast network. If your app is runnin...

We’re building a public cloud, on hardware we own. We raised money to do that, and to place some bets; one of them: GPU-enabling our customers. A progress report: GPUs aren’t going anywhere, but: GPUs aren’t going anywhere. A couple years back, we put a bunch of chips down on the bet that people shi...

JP Phillips is off to greener, or at least calmer, pastures. He joined us 4 years ago to build the next generation of our orchestration system, and has been one of the anchors of our engineering team. His last day is today. We wanted to know what he was thinking, and figured you might too. Question ...

This whole paragraph is just one long sentence. God I love just random-ass blogging again. This bit by Geoffrey Huntley is super interesting to me and, despite calling out that LLM-driven development agents like Cursor have something like a 40% success rate at actually building anything that passes ...