Cloudflare Workers vs Fly.io: Edge Functions vs Containers
Cloudflare Workers runs lightweight edge functions. Fly.io runs full containers globally. Workers for stateless edge logic; Fly.io for persistent containerised applications.
Last updated: 2026-03
In This Comparison
3-10x faster development speed when using AI coding assistants
Source: McKinsey 2025
60-80% reduction in software development costs using AI-assisted coding
Source: McKinsey 2025
Side-by-Side Comparison
| Category | Cloudflare Workers | Fly.io |
|---|---|---|
| Runtime | V8 isolates (stateless) | Docker containers |
| Pricing | $5/mo | Pay as you go |
| Persistence | Stateless (use KV/R2/D1) | Full persistent containers |
| Best For | APIs, middleware, edge logic | Backend services, databases |
| State | Durable Objects for state | Full filesystem and memory |
Cloudflare Workers
- Runtime
- V8 isolates (stateless)
- Pricing
- $5/mo
- Persistence
- Stateless (use KV/R2/D1)
- Best For
- APIs, middleware, edge logic
- State
- Durable Objects for state
Fly.io
- Runtime
- Docker containers
- Pricing
- Pay as you go
- Persistence
- Full persistent containers
- Best For
- Backend services, databases
- State
- Full filesystem and memory
Winner by Category
Best for Edge
Cloudflare WorkersLarger network and faster cold starts
Best for Flexibility
Fly.ioRun any containerised application with full persistence
Best Value
Cloudflare WorkersCheaper for lightweight edge workloads
Our Recommendation
Use Cloudflare Workers for stateless edge functions and APIs. Choose Fly.io for containerised applications that need persistent processes and state.
“The best tool depends on what you are building and how you work. There is no universal winner. Pick the one that fits your workflow and budget, then ship something.”
When to Choose Each Tool
Choose Cloudflare Workers
Building edge APIs and stateless logic
Choose Fly.io
Need persistent containers with full runtime control
Overview
Cloudflare Workers and Fly.io both distribute workloads globally but use different models. Workers runs lightweight V8 isolates that start in milliseconds but are stateless by default. Fly.io runs full Docker containers with persistent filesystems, memory, and the ability to run any application. Workers is better for lightweight, stateless tasks; Fly.io for persistent, stateful applications.
Choosing Between Them
If your workload is stateless HTTP handling, API routing, or edge logic, Workers is faster and cheaper. If you need a database server, a WebSocket server, a long-running process, or any application that requires persistence, Fly.io is the right choice. Many architectures use both: Workers at the edge for routing and caching, Fly.io for backend services.
Frequently Asked Questions
Can Cloudflare Workers run a database?
Not directly. Workers can use D1 (SQLite at the edge) or connect to external databases. Fly.io can run actual database containers.
Which is better for WebSocket applications?
Fly.io. While Workers has Durable Objects for WebSocket support, Fly.io's persistent containers are more natural for WebSocket servers.
Can I use both together?
Yes. A common pattern is Cloudflare Workers for edge routing and caching with Fly.io running backend containers.
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