Modern PaaS Platforms Cheat Sheet

Updated 2026-05-21

Next Topic: Multi-Cloud Strategies Cheat Sheet

Modern Platform as a Service (PaaS) lets teams deploy web applications, background workers, and managed databases without managing servers, clusters, or OS patches. Platforms like Fly.io, Render, Railway, Heroku, Koyeb, and DigitalOcean App Platform have redefined what "push to deploy" means, each with distinct philosophies — from Railway's usage-based simplicity to Fly.io's globally distributed Firecracker microVMs. The critical mental model: every platform trades operational control for convenience, so the right choice depends on whether your workload fits 12-factor patterns, how latency-sensitive your users are, and whether predictable billing or pay-per-use matters more. Heroku's shift to sustaining engineering in 2026 and Koyeb's acquisition by Mistral AI have made choosing the right modern PaaS more urgent than ever.

What This Cheat Sheet Covers

This topic spans 18 focused tables and 112 indexed concepts. Below is a complete table-by-table outline of this topic, spanning foundational concepts through advanced details.

Table 1: Platform Overview and PositioningTable 2: Deployment Models (Dockerfile vs Buildpack vs Source)Table 3: Regional and Edge DeploymentTable 4: Autoscaling and Scale-to-ZeroTable 5: Pricing Models and Free TiersTable 6: Managed Databases OfferedTable 7: Secrets and Environment ManagementTable 8: Custom Domains and TLS AutomationTable 9: Preview Environments and PR-Based DeploymentsTable 10: Build Caching and Pipeline IntegrationsTable 11: Persistent Storage and VolumesTable 12: Networking and Private ServicesTable 13: Observability and Log StreamingTable 14: Background Workers, Cron Jobs, and WebSocketsTable 15: Heroku Migration PatternsTable 16: IDP vs PaaS PositioningTable 17: Cost Comparison vs Hyperscaler EquivalentsTable 18: Common Limitations and Use Case Fit

Table 1: Platform Overview and Positioning

Each platform occupies a distinct niche — understanding its philosophical positioning before reading feature lists prevents choosing the wrong tool. These six are the most commonly evaluated Heroku-era replacements in 2026.

Platform	Example	Description
Railway	`Connect GitHub repo → Railpack auto-detects runtime → push to deploy`	Usage-based PaaS billed by the second; fastest path from repo to running URL; visual project canvas connects services; strong for prototyping and variable-traffic workloads.
Render	`Connect GitHub → select runtime → get onrender.com URL with zero config`	Closest philosophical Heroku replacement; flat-rate tiers with predictable billing; first-class background workers, cron jobs, and managed Postgres; eliminates per-seat fees as of 2026.
Fly.io	`fly launch → fly deploy → app runs in Firecracker microVMs across 30+ regions`	Docker-first platform running apps in Firecracker microVMs on bare metal; best for global latency-sensitive and real-time apps; steeper learning curve than Railway or Render.

Table 1: Platform Overview and Positioning

Platform	Example	Description
Railway	`Connect GitHub repo → Railpack auto-detects runtime → push to deploy`	Usage-based PaaS billed by the second; fastest path from repo to running URL; visual project canvas connects services; strong for prototyping and variable-traffic workloads.
Render	`Connect GitHub → select runtime → get onrender.com URL with zero config`	Closest philosophical Heroku replacement; flat-rate tiers with predictable billing; first-class background workers, cron jobs, and managed Postgres; eliminates per-seat fees as of 2026.
Fly.io	`fly launch → fly deploy → app runs in Firecracker microVMs across 30+ regions`	Docker-first platform running apps in Firecracker microVMs on bare metal; best for global latency-sensitive and real-time apps; steeper learning curve than Railway or Render.