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Deno vs FastAPI

Deno logo

Deno

Developer Tools

A fast, open-source, fully Node-compatible JS runtime with TypeScript baked right in

From
Free
Free plan
Yes
Full reviewWebsite
FastAPI logo

FastAPI

Web Development

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

From
Free
Free plan
Yes
Full reviewWebsite

The short version

  • Each has a real cost: Deno egress bandwidth overage costs $0.20/GB which can become expensive for high-traffic applications; 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 Deno and FastAPI actually diverge.

Attributes where Deno and FastAPI differ
AttributeDenoFastAPI
Pricing modelfreemiumopen-source
CategoryDeveloper ToolsWeb Development

Identical on both: starting price (Free), free tier (Yes), platforms (Web), user rating (Not yet rated).

What people use each for

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

Deno

  • Running TypeScript natively without transpilation overheadnot FastAPI
  • Migrating Node.js applications to secure-by-default runtimenot FastAPI
  • Deploying edge functions and serverless containers seamlesslynot FastAPI
  • Consolidating developer tools into single binarynot FastAPI

FastAPI

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

Where each one falls short

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

Deno

  • Egress bandwidth overage costs $0.20/GB which can become expensive for high-traffic applications
  • CPU time overage is $0.10/hour on Pro and Builder tiers, adding to costs for compute-intensive workloads
  • Enterprise pricing is not disclosed; requires sales contact

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

Deno

Free
  • FreeFree
    • 1 million requests/month
    • 20GB egress bandwidth
    • 10 apps
  • Pro$20/month
    • 5 million requests/month
    • 200GB egress
    • 50 apps
  • Builder$200/month
    • 25 million requests/month
    • 2,000GB egress
    • 10,000 apps
  • Enterprise$null/month
    • Custom limits on all metrics
    • 99.95% reliability SLA
    • Email support with SLA

FastAPI

Free

No published plan breakdown. See the FastAPI review.

Which should you pick?

Choose Deno if

  • You want to start without paying.
Deno review

Choose FastAPI if

  • You want to start without paying.
FastAPI review

Questions people ask

Is Deno or FastAPI better?
Neither clearly leads. Deno 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, Deno or FastAPI?
Deno starts at Free and FastAPI at Free.
Does Deno or FastAPI run on more platforms?
Both run on Web, so platform support will not decide this one for you.
Can I use Deno for free?
Both have a free tier, so you can try either at no cost before committing.
What is Deno best used for?
Deno is most often used for running typescript natively without transpilation overhead, migrating node.js applications to secure-by-default runtime, deploying edge functions and serverless containers seamlessly, consolidating developer tools into single binary. Of those, running typescript natively without transpilation overhead and migrating node.js applications to secure-by-default runtime are not what FastAPI is typically brought in for.

Answered from the vendors’ own pages

Deno: How much does Deno Deploy cost?

Deno Deploy offers a free tier at $0/month, Pro at $20/month, and Builder at $200/month. Enterprise has custom pricing. All plans include base request and bandwidth limits, with overage charges for additional usage.

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
Deno: What are Deno Deploy's overage charges?

Egress bandwidth overages cost $0.20 per GB. CPU time overages are $0.10 per hour on Pro and Builder tiers. Memory time and KV database operations also incur charges beyond included limits.

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
Deno: How many apps can I deploy on Deno's free plan?

The free tier includes 10 apps with up to 1 concurrent build. Pro tier supports 50 apps with 3 concurrent builds, and Builder supports 10,000 apps with 20 concurrent builds.

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
Deno: How many team members can access Deno Deploy?

The free tier supports up to 3 team members. Pro supports 10 team members. Builder supports 25 team members. Enterprise has custom seat limits.

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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