Fly.io
Global compute platform with sandboxed VMs for AI agents and apps
A solid pick for developers who need global edge deployment with minimal ops overhead. Sprites sandboxes uniquely handle untrusted AI code execution safely. But for simple prototypes or non-technical users, Railway or Vercel may be simpler; for deep enterprise compliance, AWS remains broader.
- Developers deploying globally distributed apps with sub-100ms latencies
- Teams building AI agents needing hardware-isolated sandboxes
- Startups scaling from prototype to millions of users without ops overhead
- Running untrusted code safely in isolated environments
- Simple static websites that are cheaper on shared hosting
- Users needing fully managed serverless like AWS Lambda
- Non-technical users preferring GUI-only deployments
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Skip Fly.io if you need a fully managed serverless platform with predictable pricing, or if your app is a simple static site that would be cheaper on Netlify or Vercel.
Going past the free trial's $5 credit incurs variable costs that can spike for bursty workloads, so monitor usage closely.
Fly.io's pay-as-you-go model suits startups that value flexibility over predictability, but costs can outpace fixed-price platforms like Railway ($5-$20/mo). For global scale, AWS or GCP may offer lower per-unit rates with reservations, but Fly.io's simplicity and sandbox features justify the premium for agent workloads.
In short
Fly.io — Global compute platform with sandboxed VMs for AI agents and apps. Best for Developers deploying globally distributed apps with sub-100ms latencies, Teams building AI agents needing hardware-isolated sandboxes, Startups scaling from prototype to millions of users without ops overhead. Free to start; paid plans from $5/mo.
What's new in Fly.io
Checked 14 days agoAcross the latest 5 updates: 4 feature updates and 1 changelog entry.
Litestream v0.5.0 is Here
Litestream v0.5.0 released with improvements to backup/restore for SQLite and a writable VFS for S3.
Unfortunately, Sprites Now Speak MCP
Sprites now support MCP, enabling coding agents to run safely with Claude, Gemini, or Codex.
The Design & Implementation of Sprites
Detailed technical deep-dive into the architecture of Fly.io's Sprites sandbox system.
Code And Let Live
Introduces sprite create command and explains how Sprites enable safe code execution.
Litestream Writable VFS
Litestream adds a writable VFS layer for syncing SQLite databases to S3 while supporting writes.
Viability Score
How likely is Fly.io to still be operational in 12 months? Based on 4 signals — momentum (how recently it shipped), wrapper dependency, revenue model, and web presence.
Last calculated: July 2026
How we score →Key Features
- Hardware-virtualized Machines (KVM-isolated containers)
- Sprites sandboxes for safe AI-generated code execution
- Checkpoint and restore entire environments
- Per-second billing for CPU and memory
- 18 global regions for sub-100ms latency
- Private networking with granular routing
- Zero-downtime deploys
- Autoscaling and monitoring
- Fast local NVMe storage
- Durable object storage (Tigris)
- Litestream v0.5.0 for SQLite backup/restore to S3 with writable VFS
- Managed Postgres databases
- Fly Kubernetes support
- SOC 2 Type 2 attested, Rust/Go stack
- MCP support for coding agents (Claude, Gemini, Codex)
About Fly.io
Fly.io is a modern compute platform for developers who want to ship fast without managing infrastructure. It uses hardware-virtualized containers called Machines that launch instantly and run only when needed, with 18 global regions for sub-100ms response times. The platform also offers Sprites—isolated sandboxes that start in under a second for running AI-generated code safely, with checkpoint/restore, per-second billing, and MCP support for agents like Claude, Gemini, and Codex. Fly.io supports popular frameworks like Rails, Phoenix, Django, Laravel, SvelteKit, Next.js, and Docker without requiring a Dockerfile. Key features include private networking, zero-downtime deploys, granular routing, monitoring, fast local NVMe storage, and durable object storage. It provides Managed Postgres, Fly Kubernetes, and integrations with Litestream for SQLite backup/restore (v0.5.0 adds improved backup/restore and writable VFS for S3). The platform is SOC 2 Type 2 attested, built on a memory-safe Rust/Go stack. Unlike Heroku or AWS, Fly.io offers a simpler experience with global edge deployment and no Terraform required.
Behind the Verdict
Fly.io hits a sweet spot between ease of use and raw compute power. If you’re deploying a globally distributed app and want sub-100ms latency without managing Kubernetes, it’s a strong bet. The Sprites feature is genuinely novel—we haven’t seen another platform that gives you hardware-isolated sandboxes for AI-generated code that start in under a second and let you checkpoint/restore entire environments. That alone makes it worth a look for teams building agents with Claude or Gemini. Where it falls short: Fly.io isn’t the cheapest option for simple static sites or serverless functions. You pay per second for what you use, so constant low-traffic workloads might cost more than a $5 VPS. The platform also expects some CLI comfort—there’s no drag-and-drop GUI for deployments. Enterprise buyers needing heavy compliance beyond HIPAA should still look at AWS or Azure. Compared to Railway or Vercel, Fly.io offers more control and global regions but a steeper initial learning curve. Compared to AWS, it’s dramatically simpler—no Terraform required—but you sacrifice breadth of services. We’d reach for Fly.io when we need to run untrusted code safely, need global edge compute, or want to scale a complex app without a dedicated ops team.
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Real-world workflow fit
Concrete scenarios for the personas Fly.io actually fits — and what changes day-one when you adopt it.
You want to deploy a Phoenix app globally with minimal ops.
Outcome: Deploy to 18 regions in minutes with zero downtime, achieving sub-100ms latency worldwide, using built-in Managed Postgres.
You need to run AI-generated code safely without risking your host.
Outcome: Spin up a Sprite sandbox with MCP support, run agent code, checkpoint the environment, and restore if something breaks—all in under a second.
You need to reduce cloud costs and improve performance.
Outcome: Migrate existing Rails app via Dockerfile or auto-detect framework, deploy to Fly's global regions, and cut latency by 50% while paying per-second for compute.
Use Cases
- Run AI agents in isolated sandboxes with MCP support
- Deploy globally distributed Rails or Phoenix apps with sub-100ms latency
- Run untrusted code, such as AI-generated code, in Sprites with checkpoint/restore
- Host distributed databases like CockroachDB or Postgres across regions
- Deploy ephemeral worker VMs that auto-scale and auto-stop
- Fork VMs like processes for on-demand compute
Models Under the Hood
as of 2026-07-15
12-month cost
Project the real annual outlay, including the implied monthly cost when only an annual tier is published.
Vendor list price only. Add-on usage, seat overages, and contract minimums are surfaced under Hidden costs & gotchas.
Plans compared
For each published Fly.io tier: who it actually fits, and what it adds vs. the previous tier. Cross-reference the cost calculator above for projected annual outlay.
Pay-as-you-go
Variable per-second billing; $5 free usage credit included
Ideal for
Developers and small teams who want to start free and scale usage-based, with no upfront commitment.
What this tier adds
Starting tier: per-second billing, free egress within regions, unlimited users, private networking, SSO, ACLs, and access tokens.
Machine Reservation
40% off pay-as-you-go
Ideal for
Teams with predictable workloads who want to reduce compute costs by pre-paying.
What this tier adds
Pre-pay for reserved capacity and get 40% off pay-as-you-go rates for committed usage.
Support - Standard
$29/mo
Ideal for
Production teams that need dedicated support and financial protection from accidental deployments.
What this tier adds
Adds $29/mo for dedicated support engineers, guaranteed response times, and accidental deployment waivers.
HIPAA Compliance
$99/mo
Ideal for
Healthcare startups and enterprises that need HIPAA BAA and SOC 2 compliance for their workloads.
What this tier adds
$99/mo adds HIPAA BAA and SOC 2 attestation on top of pay-as-you-go infrastructure.
Support - Premium
$199/mo
Ideal for
Teams with critical uptime needs that require faster response and priority support.
What this tier adds
Costs $199/mo, adds priority support and faster response times over Standard.
Support - Enterprise
$2,500+/mo
Ideal for
Large organizations needing custom SLAs and emergency support with dedicated engineering.
What this tier adds
$2,500+/mo with custom SLA, emergency support, and all Premium features.
Where the pricing makes sense
The company stage and team size where Fly.io's pricing actually pencils out — and where peers do it cheaper.
Fly.io's pay-as-you-go model suits startups that value flexibility over predictability, but costs can outpace fixed-price platforms like Railway ($5-$20/mo). For global scale, AWS or GCP may offer lower per-unit rates with reservations, but Fly.io's simplicity and sandbox features justify the premium for agent workloads.
Setup time & first value
How long it actually takes to get something useful out of Fly.io — broken out by persona, not the marketing-page minute.
First deploy takes about 10 minutes: install flyctl CLI, run 'fly launch' (auto-detects framework), then 'fly deploy'. If using Docker, add 5 minutes. Sprites: create a sprite in seconds via CLI. Migrating a Heroku app: follow the migration guide—about 30 minutes for a typical Rails app.
Switching to or from Fly.io
How to bring data in from common predecessors and how to get it back out — written for the switcher, not the buyer.
- →From Heroku: Use the built-in migration guide—export your app, set env vars, deploy via 'fly launch' and 'fly deploy'.
- →From Railway: Dockerfile-based—just point flyctl at your repo and deploy.
- →From AWS ECS: Extract your Dockerfile, use 'fly launch', then configure private networking and volumes.
- ↗To Railway: Export your fly.toml and Dockerfile, deploy via Railway CLI.
- ↗To AWS: Use 'fly machine list' to inventory instances, then replicate in ECS/Fargate with CloudFormation.
- ↗To Google Cloud Run: Convert fly.toml to Cloud Run service YAML, export env vars.
Integrations
Resources & Guides
- Documentationfly.io
Docs · Fly.io
Full product docs from fly.io
- Quickstartfly.io
Getting Started · Fly.io
Get up and running fast from fly.io
- Documentationfly.io
Machines · Fly.io
Full product docs from fly.io
- Quickstartfly.io
Getting Started · Fly.io
Get up and running fast from fly.io
- Quickstartfly.io
Getting Started · Fly.io
Get up and running fast from fly.io
- Documentationfly.io
Mpg · Fly.io
Full product docs from fly.io
- Documentationfly.io
Kubernetes · Fly.io
Full product docs from fly.io
- Documentationfly.io
Volumes · Fly.io
Full product docs from fly.io
- Documentationfly.io
Security · Fly.io
Full product docs from fly.io
- Documentationfly.io
Networking · Fly.io
Full product docs from fly.io
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