Fly.io

Fly.io offers a platform for running applications and AI agents on hardware-isolated virtual machines (VMs). It focuses on placing these services close to users for lower latency. The platform provides two main components: "Sprites" for AI agents and "Machines" for general application deployment. Sprites are designed to run AI agents, offering features like persistent storage, automatic checkpointing, and the ability to sleep when not in use, waking up with their state intact. Machines are for deploying web applications and services, booting quickly and scaling based on demand.

Fly.io emphasizes that agents get their own Linux box with persistent disk, allowing them to retain state and continue work. The platform supports deploying agent-built applications directly, providing an HTTPS URL for each Sprite. It also offers features like a durable filesystem with object-storage backed block devices, automatic disk sizing up to 100 GB, and automatic checkpointing for Sprites. For security, it allows running untrusted code in hardware-isolated VMs with egress policies. Fly.io also provides "Sprites Connectors" for managing API credentials centrally, allowing Sprites to connect to external services like OpenRouter, GitHub, or Slack without tokens residing on the Sprite itself.

Best for

• Running AI agents that require persistent state and dedicated compute resources.
• Deploying full-stack applications that need to be globally distributed.
• Developers who want to run untrusted code in isolated environments.
• Teams looking for a platform that scales from prototyping to production without re-architecting.
• Managing API access for agents through centralized connectors.

Frequently asked questions

What is a Fly.io Sprite?

A Sprite is a hardware-isolated Linux virtual machine specifically designed to run AI agents. It includes features like persistent storage and automatic checkpointing, allowing agents to retain their state and resume work.

How does Fly.io handle persistent storage for agents?

Fly.io uses a "Sprite Block Device" which is an object-storage backed, durable filesystem. This allows Sprites to go to sleep and wake up with all their data and installed dependencies intact, and it can grow up to 100 GB per Sprite.

Can I deploy regular web applications on Fly.io?

Yes, Fly.io offers "Machines" which are hardware-isolated VMs for deploying web applications and services. These machines boot quickly and can scale to handle varying traffic loads.

What kind of support does Fly.io offer?

Fly.io states that its support team consists of engineers who write code and can assist with technical issues, including complex networking problems.

Does Fly.io offer a free tier?

The website mentions "Start free," indicating that there is likely a free tier or a way to begin using the service without immediate cost, though specific details are not provided on the homepage.

How does Fly.io manage security for agent connections to external services?

Fly.io uses "Sprites Connectors" to manage credentials. This allows configuring connections to services like OpenRouter or GitHub once, and then Sprites can access them through an API gateway without the actual token landing on the Sprite.

Alternatives

• Vercel – Pick Vercel if you are primarily deploying frontend web applications and serverless functions.
• Render – Choose Render for a fully managed cloud platform that supports web services, databases, and cron jobs with a focus on ease of use.
• Railway – Consider Railway for deploying web apps and services with automatic scaling and a focus on developer experience.
• AWS – Use AWS if you need a comprehensive suite of over 200 cloud services for a wide range of applications and infrastructure needs.
• Heroku – Select Heroku for a platform-as-a-service experience with simple Git-push deployments, especially for traditional web applications.