Heroku vs. Fly.io

As AI technology advances, choosing the right platform is crucial for your team's speed, governance, and long-term success. Both Heroku and Fly.io have their strengths. The sections below compare them across developer experience, scalability, and total cost of ownership.

As AI technologies evolve, delivering and scaling applications has become essential for powering modern businesses, from AI startups to large-scale enterprises. There are various solutions available, including comprehensive cloud operating systems, managed Platform-as-a-Service (PaaS), and traditional IaaS. Selecting the right platform is crucial for your team's velocity, governance, and long-term success.

Heroku and Fly.io both bring unique strengths to application delivery, each with its own capabilities and limitations. The best choice depends on your specific use case and requirements. In the following sections, we'll compare both platforms regarding developer experience, scalability, and total cost of ownership, helping you determine the most suitable option for your needs—even if it's not us.

Heroku vs. Fly.io at a Glance

Feature	Heroku	Fly.io
Infrastructure	Proprietary PaaS	Edge micro-VMs (Firecracker)
Source Available
Deployment Options	Cloud only Private Spaces: Enterprise	Cloud only
Free Trial	No free tier (Eco $5/mo)	Free allowance (shared CPU, limited)
Max vCPU per Service	Performance-2XL: 128GB	Plan-based (per VM size)
Max RAM per Service	Performance-2XL: 128GB	Plan-based (per VM size)
Custom Domains	Multiple (per app)
Replicas per Service	Plan-based (dyno limits)	(within org limits)
Cron Jobs	Via add-on (Scheduler)	Scheduled machines
Log Retention	Limited (1500 lines; add-ons)	Limited (plan-based)
Scale-to-Zero	Eco dynos sleep	(saves on idle)
App Marketplace

Cost evidence

Monthly Cost Examples: Plans vs. Usage Billing

Estimates use the listed average CPU and RAM for a 30-day month. Storage and egress are excluded unless a platform note says otherwise.

Workload examplePlatform and monthly costEstimated difference

Small API

2 vCPU, 4GB RAM, 24/7

HerokuEstimate

~$200/mo

Fly.ioEstimate

~$85/mo

Heroku 71% lower

Medium App

8 vCPU, 16GB RAM, 24/7

HerokuEstimate

~$800/mo

Fly.ioEstimate

~$300/mo

Heroku 57% lower

Production Stack

16 vCPU, 32GB RAM, 24/7

HerokuEstimate

~$1,600/mo

Fly.ioEstimate

~$600/mo

Heroku 15% lower

Small API

2 vCPU, 4GB RAM, 24/7

HerokuEstimate

~$200/mo

Fly.ioEstimate

~$85/mo

Heroku 71% lower

Medium App

8 vCPU, 16GB RAM, 24/7

HerokuEstimate

~$800/mo

Fly.ioEstimate

~$300/mo

Heroku 57% lower

Production Stack

16 vCPU, 32GB RAM, 24/7

HerokuEstimate

~$1,600/mo

Fly.ioEstimate

~$600/mo

Heroku 15% lower

Heroku calculation: Standard-2X dynos $50/mo each, scaled to approximate RAM requirements

Fly.io calculation: estimated using always-on VM pricing (CPU + RAM) across 720 hours/month

Sources:Heroku Pricing·Fly.io Pricing

Heroku Overview

Heroku is a mature Platform-as-a-Service (PaaS) built around git-based deployment and buildpacks. It runs applications on dynos (managed Linux containers), pairs seamlessly with the Heroku CLI and GitHub integration, and offers Pipelines, Review Apps, and a large add-ons marketplace. The platform abstracts infrastructure details for teams that want a fast path from code to production with a predictable, dyno-based pricing model.

Fly.io Overview

Fly.io is an edge application platform that runs apps as lightweight Firecracker micro-VMs across a global network. It emphasizes Dockerfile-first deployments and a powerful CLI (`flyctl`) for fast, scriptable workflows. Fly.io provides Anycast networking, global routing, per-region scaling, and scale-to-zero for idle workloads, making it a strong fit for latency-sensitive apps and globally distributed teams.