Fly.io vs Vercel: Frontend vs Backend Focus
Fly.io and Vercel serve different primary use cases. Here's when to use each — and when to combine them.
Fly.io and Vercel aren't really competitors in the traditional sense — they serve different primary use cases. Vercel excels at frontend deployment; Fly.io excels at persistent backend services.
Vercel's Strength
Vercel is purpose-built for frontend frameworks (Next.js, Svelte, Astro). Edge functions, ISR, image optimization, and instant rollbacks are best-in-class. If your application is a marketing site, SaaS frontend, or content platform, Vercel is hard to beat.
Fly.io's Strength
Fly.io is built for applications that need persistent processes — long-running servers, TCP connections, background workers. Things that don't fit the serverless model. AI backends, chatbots, and agents run naturally on Fly.io.
The Complementary Stack
Many teams use both: Vercel for the frontend, Fly.io + OpenClaw for the AI backend. Your Next.js app calls your OpenClaw-powered bot API on Fly.io. Best of both worlds.
When They're Directly Comparable
Both can host: Node.js APIs, serverless functions (sort of on Fly), static files. But:
- Vercel's serverless model has cold starts and execution timeouts
- Fly.io's persistent VMs have none of those limitations
Pricing Comparison
Vercel: Free for personal projects, usage-based for teams. Unlimited bandwidth on paid plans.
Fly.io: Raw compute pricing. Can be cheaper or more expensive depending on usage patterns. No bandwidth limits.
Summary
Use Vercel for your frontend. Use Fly.io + OpenClaw for your AI backend. They're complementary platforms, not either-or choices.