Fly.io
Prometheus
| Feature | Fly.io | Prometheus |
|---|---|---|
| Pricing | Free / from $0/mo | Free only |
| Free Plan | ✓ Yes | ✓ Yes |
| Rating | 4.2 / 5 | 4.5 / 5 |
| Best For | full-stack-developers, global-apps, edge-computing, hobby-projects | devops-engineers, sre-teams, kubernetes-users, infrastructure-teams |
| Founded | 2017 | 2012 |
| Global Deployment | ✓ | ✗ |
| Firecracker Vms | ✓ | ✗ |
| Fly Postgres | ✓ | ✗ |
| Auto Scaling | ✓ | ✗ |
| Volumes | ✓ | ✗ |
| Private Networking | ✓ | ✗ |
| Gpu Support | ✓ | ✗ |
| Metrics Collection | ✗ | ✓ |
| Alerting | ✗ | ✓ |
| Promql | ✗ | ✓ |
| Service Discovery | ✗ | ✓ |
| Grafana Integration | ✗ | ✓ |
| Multi Dimensional Data | ✗ | ✓ |
✓ Fly.io Pros
- Deploy apps globally to 30+ regions easily
- Built-in Postgres and Redis for data at the edge
- Generous free tier for hobby projects
- Firecracker VMs start in milliseconds
✗ Fly.io Cons
- Operational complexity for simple apps
- Documentation can be hard to navigate
- Billing surprises if auto-scaling triggers unexpectedly
✓ Prometheus Pros
- Free and open-source
- Powerful query language
- Great Kubernetes integration
- Active community
✗ Prometheus Cons
- No built-in long-term storage
- Complex setup
- Steep learning curve
The Verdict
Fly.io is built for full stack developers and global apps, with a focus on global-deployment and firecracker-vms. Prometheus targets devops engineers and sre teams and leads with metrics-collection and alerting.
Prometheus uses custom enterprise pricing, while Fly.io starts at $0/mo — a tangible advantage for teams with a fixed budget.
Both offer free plans, so you can test each with your real workflow before committing to a subscription.
Feature-wise, Fly.io offers broader built-in capabilities (7 features vs 6), while Prometheus takes a more focused approach — which can mean a simpler, faster onboarding experience.
Bottom line: Prometheus has a slight overall edge — but if deploy apps globally to 30+ regions easily matters most to you, Fly.io may still be the right call.