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Web Development · head to head

.NET vs FastAPI

.NET logo

.NET

Web Development

Free, cross-platform, open source developer platform

From
Free
Rated
-
Full reviewWebsite
FastAPI logo

FastAPI

Web Development

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

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: .NET .NET 8 and .NET 9 both reach end of support on 10 November 2026, per dotnet.microsoft.com/en-us/platform/support/policy (Aug 2026), forcing an upgrade to .NET 10 by that date; FastAPI no built-in ORM, requires separate database libraries
  • Prices and features above were last checked on 29 August 2026.

Where they differ

Only the attributes on which .NET and FastAPI actually diverge.

Attributes where .NET and FastAPI differ
Attribute.NETFastAPI

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.

.NET

  • Web development with ASP.NET Core and Entity Frameworknot FastAPI
  • Cloud-native application development for Azurenot FastAPI
  • Mobile and desktop apps with .NET MAUI cross-platform frameworknot FastAPI
  • AI and machine learning applications using C#not FastAPI

FastAPI

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

Where each one falls short

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

.NET

  • .NET 8 and .NET 9 both reach end of support on 10 November 2026, per dotnet.microsoft.com/en-us/platform/support/policy (Aug 2026), forcing an upgrade to .NET 10 by that date
  • Standard Term Support releases get only 2 years of patches versus 3 years for Long Term Support releases, per Microsoft's own support policy page, so teams on an STS release face a shorter upgrade cycle

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

Pricing, plan by plan

.NET

Free

No published plan breakdown. See the .NET review.

FastAPI

Free

No published plan breakdown. See the FastAPI review.

Which should you pick?

Choose .NET if

  • You want to start without paying.
.NET review

Choose FastAPI if

  • You want to start without paying.
FastAPI review

Questions people ask

Is .NET or FastAPI better?
Neither clearly leads. .NET starts at Free and FastAPI at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, .NET or FastAPI?
.NET starts at Free and FastAPI at Free.
Does .NET or FastAPI run on more platforms?
Both run on Web, so platform support will not decide this one for you.
Can I use .NET for free?
Both have a free tier, so you can try either at no cost before committing.
What is .NET best used for?
.NET is most often used for web development with asp.net core and entity framework, cloud-native application development for azure, mobile and desktop apps with .net maui cross-platform framework, ai and machine learning applications using c#. Of those, web development with asp.net core and entity framework and cloud-native application development for azure are not what FastAPI is typically brought in for.

Answered from the vendors’ own pages

.NET: Is .NET free to use?

Yes. .NET is completely free and open-source, available on GitHub.

Source
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
.NET: What platforms does .NET support?

.NET supports Windows, Linux, macOS, and Docker. A single C# codebase can run across multiple platforms including iOS, Android, and cloud environments.

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
.NET: How large is the .NET ecosystem?

NuGet provides 390,000+ unique packages with 50,000+ new packages added annually. .NET has 474K+ GitHub stars and active community support across multiple platforms.

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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