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Fly.io vs Heroku: Complete Platform Comparison for 2025

Both Fly.io and Heroku offer Platform-as-a-Service (PaaS) solutions that abstract infrastructure management from developers, but they take fundamentally different approaches to deployment, scaling, and pricing. This comprehensive comparison examines both platforms across key decision factors to help developers choose the right hosting solution.

Platform Overview

Heroku launched in 2007 as one of the first PaaS offerings, built on Amazon Web Services infrastructure. It pioneered the concept of git-based deployments and has maintained its position as a developer-friendly platform with extensive add-on ecosystem. Heroku eliminated its free tier in November 2022 and now focuses on paid plans starting with Eco dynos.

Fly.io emerged as a modern alternative focused on edge computing and global deployment. The platform uses hardware-virtualized containers running on Firecracker microVMs across 35+ regions worldwide. Fly.io transitioned to a usage-based pricing model in October 2024, offering more granular control over infrastructure costs.

Pricing and Cost Structure

Heroku Pricing (2025)

Heroku's current pricing structure centers around dynos with different performance tiers:

  • Eco Dynos: $5/month for 1,000 shared dyno hours across all apps. Dynos sleep after 30 minutes of inactivity
  • Basic Dynos: $7/month per dyno, always-on with no sleep functionality
  • Standard-1x: $25/month per dyno with 512MB RAM
  • Standard-2x: $50/month per dyno with 1GB RAM
  • Performance-M: $250/month per dyno with 2.5GB RAM
  • Performance-L: $500/month per dyno with 14GB RAM

Additional costs include database add-ons (starting at $5/month for Postgres Hobby), and various third-party services through the Heroku marketplace.

Fly.io Pricing (2025)

Fly.io operates on usage-based billing with the following structure:

  • Shared CPU: Starting at approximately $0.0000077/second for shared-cpu-1x (256MB RAM)
  • Dedicated CPU: Higher performance options with dedicated resources
  • Storage: Volume pricing per GB-hour
  • Bandwidth: Regional pricing varies, with increases implemented in phases starting July 2024
  • Free Tier: 3 shared-cpu-1x machines and 3GB persistent volume storage for new accounts

The platform offers 40% discounts for reserved compute blocks and includes autostop/autostart functionality to reduce costs during low-traffic periods.

Cost Comparison Analysis

For equivalent specifications, Fly.io typically costs significantly less than Heroku. A Standard-1x Heroku dyno ($25/month) with 512MB RAM equates to approximately $3.19/month on Fly.io when running continuously. However, Fly.io's usage-based model can lead to unpredictable costs at scale, particularly when adding regions or scaling resources.

Deployment and Ease of Use

Heroku Deployment Experience

Heroku maintains its reputation for deployment simplicity through git-based workflows:

  • Git Integration: Push code directly via git push heroku main
  • Automatic Detection: Platform automatically detects application type and configures buildpacks
  • Buildpack System: Extensive library of official and community buildpacks for different languages
  • Pipeline Support: Built-in CI/CD with review apps and staging environments
  • Add-on Provisioning: One-click installation of databases, monitoring tools, and other services

Fly.io Deployment Experience

Fly.io offers more infrastructure control while maintaining developer convenience:

  • Dockerfile-Based: Applications packaged as Docker containers for consistent deployment
  • Automatic Generation: CLI generates Dockerfiles for popular frameworks (Rails, Phoenix, Django, Node.js)
  • Configuration Management: fly.toml files provide granular control over deployment settings
  • Multi-Region Deployment: Deploy applications across multiple regions with single command
  • Machine Management: Direct control over individual machines and their configurations

Heroku provides a more streamlined experience for developers who prefer minimal infrastructure involvement, while Fly.io offers greater flexibility for teams comfortable with containerization concepts.

Performance and Scalability

Heroku Performance Characteristics

  • Dyno Architecture: Applications run in isolated Linux containers on shared or dedicated infrastructure
  • Boot Times: Standard application startup times without optimization
  • Scaling: Horizontal scaling by increasing dyno count, vertical scaling by changing dyno types
  • Geographic Distribution: Single-region deployment with optional multi-region add-ons
  • Sleep Behavior: Eco dynos sleep after 30 minutes, causing cold start delays

Fly.io Performance Characteristics

  • Firecracker MicroVMs: Hardware-virtualized containers with approximately 300ms boot times
  • Global Edge Deployment: Applications automatically deployed across 35+ regions
  • Anycast Routing: BGP Anycast routes user requests to nearest geographic instance
  • Instant Scaling: Machines start fast enough to handle individual HTTP requests
  • Always-On Option: Machines can run continuously or scale to zero based on demand

Fly.io demonstrates superior performance for globally distributed applications requiring low latency, while Heroku performs adequately for regional deployments with traditional scaling patterns.

Features and Capabilities

Heroku Feature Set

  • Add-on Marketplace: Over 200 add-ons including databases, monitoring, logging, and analytics
  • Heroku Postgres: Managed PostgreSQL with automatic backups and high availability options
  • Heroku Redis: Managed Redis instances with different performance tiers
  • Process Types: Support for web, worker, and scheduler processes defined in Procfile
  • Config Vars: Environment variable management through web interface or CLI
  • Release Management: Automatic release tracking with rollback capabilities

Fly.io Feature Set

  • Global Networking: Private WireGuard-based networking connecting all deployed instances
  • Persistent Volumes: Block storage that can be attached to machines across regions
  • PostgreSQL Clusters: Built-in PostgreSQL hosting with global replication support
  • Edge Functions: JavaScript runtime for lightweight compute tasks
  • Machine Management: Direct control over individual virtual machines
  • Docker Support: Native container deployment with custom Dockerfile support

Heroku excels in add-on ecosystem breadth, while Fly.io focuses on infrastructure primitives and global deployment capabilities.

Developer Experience

Heroku Developer Workflow

Heroku prioritizes developer productivity through abstraction:

  • Zero DevOps: Platform handles all infrastructure management automatically
  • Extensive Documentation: Comprehensive guides for common deployment scenarios
  • Dashboard Interface: Web-based application management and monitoring
  • CLI Tools: Comprehensive command-line interface for all platform operations
  • Integration Ecosystem: Native integrations with development tools and services

Fly.io Developer Workflow

Fly.io balances ease of use with infrastructure transparency:

  • Infrastructure Visibility: Developers maintain awareness of underlying infrastructure
  • Configuration Control: Detailed control over deployment specifications
  • Command-Line First: Primary interaction through flyctl CLI tool
  • Documentation Quality: Technical documentation focused on platform capabilities
  • Community Support: Active community forums and Discord channels

Heroku appeals to teams prioritizing rapid deployment with minimal infrastructure knowledge, while Fly.io suits developers comfortable with containerization and infrastructure concepts.

Security and Compliance

Heroku Security Features

  • SOC 2 Type II Compliance: Audited security controls and procedures
  • Data Encryption: Encryption in transit and at rest for all applications
  • Private Spaces: Isolated network environments for enterprise applications
  • Single Sign-On: Integration with enterprise identity providers
  • Vulnerability Scanning: Automated security scanning of application dependencies
  • DDoS Protection: Built-in protection against distributed denial-of-service attacks

Fly.io Security Features

  • Hardware Isolation: Firecracker microVMs provide strong isolation between applications
  • WireGuard VPN: Encrypted private networking between application instances
  • Certificate Management: Automatic TLS certificate provisioning and renewal
  • Edge Security: Global distribution reduces single points of failure
  • Access Controls: Granular permissions for team collaboration
  • Compliance: Working toward enterprise compliance certifications

Both platforms provide adequate security for most applications, with Heroku offering more mature enterprise compliance features.

Support and Documentation

Heroku Support Options

  • Documentation: Extensive Dev Center with tutorials, references, and best practices
  • Community Support: Stack Overflow integration and community forums
  • Ticket Support: Available for paid plans with response time guarantees
  • Enterprise Support: Dedicated support teams for enterprise customers
  • Status Page: Detailed incident reporting and platform status updates

Fly.io Support Options

  • Technical Documentation: Comprehensive docs covering platform features and APIs
  • Community Forums: Active community discussion and troubleshooting
  • Discord Channel: Real-time community support and platform updates
  • GitHub Issues: Public issue tracking for platform bugs and feature requests
  • Direct Support: Email support with varying response times based on plan

Heroku provides more structured support options, while Fly.io relies heavily on community engagement and self-service documentation.

When to Choose Each Platform

Choose Heroku When:

  • Rapid Prototyping: Need to deploy applications quickly without infrastructure concerns
  • Add-on Requirements: Require extensive third-party integrations available through the marketplace
  • Team Expertise: Team lacks containerization or infrastructure management experience
  • Enterprise Features: Need mature compliance, security, and support options
  • Regional Deployment: Application serves users primarily from a single geographic region
  • Budget Predictability: Prefer fixed monthly costs over usage-based pricing

Choose Fly.io When:

  • Global Distribution: Users are geographically distributed requiring low latency
  • Cost Optimization: Need precise control over infrastructure costs
  • Performance Requirements: Applications require fast cold starts and edge deployment
  • Container Experience: Team comfortable with Docker and containerization concepts
  • Infrastructure Control: Need granular control over deployment configuration
  • Modern Architecture: Building microservices or distributed applications

Conclusion

Heroku and Fly.io represent different philosophies in Platform-as-a-Service offerings. Heroku continues to excel in developer productivity through abstraction, extensive add-on ecosystem, and mature enterprise features. However, its pricing structure can become expensive at scale, and geographic distribution options remain limited.

Fly.io offers compelling advantages for globally distributed applications through edge deployment, competitive pricing, and modern infrastructure primitives. The platform suits teams comfortable with containerization concepts and seeking infrastructure transparency. However, its smaller ecosystem and usage-based pricing model may present challenges for some development teams.

The choice between platforms ultimately depends on specific project requirements, team expertise, geographic distribution needs, and budget constraints. Heroku remains the safer choice for teams prioritizing simplicity and ecosystem maturity, while Fly.io appeals to developers seeking performance optimization and cost control in globally distributed applications.