TL;DR verdict: Use Fly.io when you want raw control — Machines, regions, any runtime, per-second billing. Use AgentCell when the workload is twenty mostly-idle tools shared with named people: Fly’s ~$2/mo-per-app floor and DIY-auth shape tax exactly that sprawl.
Where Fly.io wins (honestly)
- Per-second billing with auto-suspend. The closest any PaaS comes to our economics, and a genuine innovation for bursty workloads.
- Control. Firecracker microVMs, real regions, arbitrary runtimes — the most “real computer” of the simple PaaSs.
- No seats, no tiers games. Straightforward machine pricing engineers can reason about.
We respect Fly’s model enough to have learned from it. The gaps are narrower here than anywhere else — and still structural.
Gap 1: the $2/mo-per-app floor
A minimal always-on shared-cpu micro-VM runs roughly $2/mo in compute, plus storage and IP — and the free tier has been gone since 2024. Two dollars is nothing for one app. For twenty rarely-opened tools it is ~$40+/mo before anyone clicks anything, which quietly reintroduces the pruning instinct: “do we still need that one?” Once people prune, accumulation dies, and accumulation is the whole product. Idle cells on AgentCell sleep to zero and bill nothing for compute — the twentieth experiment costs nothing to keep.
(Also worth knowing: Fly’s growth appears to have plateaued — ~$11.2M revenue in 2024 against Render/Railway’s $100M 2026 raises. Directional, secondary-sourced, but relevant to “who will still be investing in this in 2028.”)
Gap 2: no identity or sharing layer
Fly gives you Machines and networking; who may open the app is entirely your code’s problem. Same stitching as everywhere: an auth vendor, a second bill with enterprise floors, session logic duplicated across tools. And stopped Machines wake in multi-second times from cold — acceptable for services, awkward for “click this link in a meeting.”
Side-by-side
| Fly.io | AgentCell | |
|---|---|---|
| Billing | Per-second, auto-suspend; ~$2/mo always-on floor | Per-cell consumption, idle ~zero |
| Runtime control | Full — any image, real regions | Curated + org-customizable environments |
| Free tier | Removed 2024 | Free idle by design |
| Share with colleagues | DIY auth in every app | Share list + identity-aware front door |
| Wake from stopped | Multi-second | Wake-latency target measured pre-launch |
| Best for | Engineers wanting machine-level control | Teams wanting tools without operating machines |
Fit checklist
Use AgentCell when: the audience is people with names, not services; idle cost across many tools must be ~zero; nobody wants to think about Machines.
Stay on Fly when: you need region placement, custom networking, or exotic runtimes; per-second billing already fits; auth is handled upstream.
FAQ
Is AgentCell cheaper than Fly for one busy app? Not necessarily — a single always-warm service may cost the same or less on Fly. The savings appear across many idle apps, which is the workload we’re built for.
Do you offer Fly-like region control? Data residency is a region choice in our design, not a thesis. Fine-grained region placement per cell is not a launch feature.
Running twenty Fly apps that mostly idle? Deploy now.