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FastAPI vs Ruby on Rails

FastAPI logo

FastAPI

Web Development

A modern, fast, high-performance web framework for building APIs with Python

From
Free
Rated
-
Full reviewWebsite
Ruby on Rails logo

Ruby on Rails

Web Development

A full-stack framework for building web applications

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: FastAPI no built-in ORM, requires separate database libraries; Ruby on Rails licensed under the MIT License per rubyonrails.org; as open source software it has no paid tier or vendor price to compare
  • Prices and features above were last checked on 29 August 2026.

Where they differ

Only the attributes on which FastAPI and Ruby on Rails actually diverge.

Attributes where FastAPI and Ruby on Rails differ
AttributeFastAPIRuby on Rails

Identical on both: starting price (Free), pricing model (open-source), free tier (Yes), platforms (Web), user rating (Not yet rated), category (Web Development).

What people use each for

The jobs each tool is most often brought in to do.

FastAPI

  • Building production-ready REST APIs with automatic validationnot Ruby on Rails
  • Serving machine learning model predictions as REST servicesnot Ruby on Rails
  • Building crisis management and orchestration platformsnot Ruby on Rails
  • Enabling real-time APIs with WebSocket connectionsnot Ruby on Rails
  • Rapid API development reducing boilerplate code significantlynot Ruby on Rails

Ruby on Rails

  • Building e-commerce platforms that scale from startup to IPOnot FastAPI
  • Developing SaaS applications with consistent conventions across teamsnot FastAPI
  • Creating marketplace platforms like Airbnb with transactional workflowsnot FastAPI
  • Integrating cloud file storage and real-time WebSocket updatesnot FastAPI
  • Enforcing encryption and security protections against common attacksnot FastAPI

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

FastAPI

  • No built-in ORM, requires separate database libraries
  • Python-only, cannot build with other languages
  • Async/await learning curve for developers new to async programming
  • Production deployment requires separate ASGI server configuration

Ruby on Rails

  • Licensed under the MIT License per rubyonrails.org; as open source software it has no paid tier or vendor price to compare
  • The framework is Ruby-only by design, per rubyonrails.org's own description of its convention over configuration approach, requiring the Ruby runtime rather than supporting alternate languages

Pricing, plan by plan

FastAPI

Free

No published plan breakdown. See the FastAPI review.

Ruby on Rails

Free

No published plan breakdown. See the Ruby on Rails review.

Which should you pick?

Choose FastAPI if

  • You want to start without paying.
FastAPI review

Choose Ruby on Rails if

  • You want to start without paying.
Ruby on Rails review

Questions people ask

Is FastAPI or Ruby on Rails better?
Neither clearly leads. FastAPI starts at Free and Ruby on Rails at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, FastAPI or Ruby on Rails?
FastAPI starts at Free and Ruby on Rails at Free.
Does FastAPI or Ruby on Rails run on more platforms?
Both run on Web, so platform support will not decide this one for you.
Can I use FastAPI for free?
Both have a free tier, so you can try either at no cost before committing.
What is FastAPI best used for?
FastAPI is most often used for building production-ready rest apis with automatic validation, serving machine learning model predictions as rest services, building crisis management and orchestration platforms, enabling real-time apis with websocket connections. Of those, building production-ready rest apis with automatic validation and serving machine learning model predictions as rest services are not what Ruby on Rails is typically brought in for.

Answered from the vendors’ own pages

FastAPI: Is FastAPI free to use?

Yes. FastAPI is free and open-source under the MIT License. It costs nothing to download, use, or deploy in production. An optional paid service, FastAPI Cloud, offers one-command deployment for additional convenience, but the core framework is free.

Source
Ruby on Rails: Is Ruby on Rails free?

Yes, Ruby on Rails is free and open-source, licensed under the MIT License. There are no costs associated with using or distributing the framework.

Source
FastAPI: Can I use FastAPI for commercial applications?

Yes. FastAPI's MIT License permits unrestricted commercial use, modification, and distribution. You can build and sell products powered by FastAPI without licensing fees or restrictions.

Source
Ruby on Rails: What is Ruby on Rails licensed under?

Ruby on Rails is licensed under the MIT License, a permissive open-source license that allows commercial and private use.

Source
FastAPI: Does FastAPI include a database or ORM?

No. FastAPI does not include a built-in database or ORM. You must add separate libraries like SQLAlchemy for database access. This gives flexibility to choose the database solution best suited to your project.

Source
FastAPI: What Python versions does FastAPI support?

FastAPI supports Python 3.7 and later. Older Python versions are not compatible, so you must run at least Python 3.7 to use FastAPI.

Source
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