FastAPI vs Flask
type: Article
description: FastAPI is a modern Python web framework built on Starlette that prioritizes speed and automatic API documentation with async support by default, while Flask is a lightweight, minimalist framework that emphasizes simplicity and flexibility with synchronous request handling. FastAPI's built-in features result in ~3x faster request handling and automatic OpenAPI/Swagger documentation, whereas Flask requires manual setup for these capabilities.
language: en-US
date published: 2026-07-09T11:45:15.871Z
date created: 2026-07-09T11:45:15.871Z
date modified: 2026-07-09T11:45:15.918Z
content reference time: 2026-07-09T11:45:15.918Z
author: A Versus B
publisher: A Versus B
about: FastAPI
about: Flask
abstract: FastAPI is a modern Python web framework built on Starlette that prioritizes speed and automatic API documentation with async support by default, while Flask is a lightweight, minimalist framework that emphasizes simplicity and flexibility with synchronous request handling. FastAPI's built-in features result in ~3x faster request handling and automatic OpenAPI/Swagger documentation, whereas Flask requires manual setup for these capabilities.
text: Request Performance (requests/sec). Async/Await Support. Automatic API Documentation. Learning Curve (hours to productivity). Ecosystem Maturity (years since release). Built-in Data Validation. GitHub Stars (as of 2026)
conclusion text: Choose FastAPI if you're building modern REST APIs that require high performance, automatic documentation, async operations, or type safety with built-in validation—ideal for microservices, real-time applications, and teams prioritizing developer experience. Choose Flask if you prioritize simplicity, have an existing codebase, need a lightweight framework for small projects, or prefer minimal dependencies and maximum flexibility in architecture decisions.
additional property: Async/Await Native Support
  type: PropertyValue
  value: FastAPI: Yes, built-in by default | Flask: No, requires external libraries
additional property: Automatic API Documentation
  type: PropertyValue
  value: FastAPI: Yes, OpenAPI/Swagger auto-generated | Flask: No, manual setup required
additional property: Time to First API (Learning Curve)
  type: PropertyValue
  value: FastAPI: 15-25 hours | Flask: 5-10 hours
  value reference: Flask
additional property: Core Framework Size
  type: PropertyValue
  value: FastAPI: ~300 KB | Flask: ~60 KB
  value reference: Flask
additional property: Time Since Initial Release
  type: PropertyValue
  value: FastAPI: 4 years (2021) | Flask: 18 years (2010)
  value reference: Flask
additional property: Throughput (Requests/Second)
  type: PropertyValue
  value: FastAPI: 8,000-12,000 | Flask: 400-600
  value reference: FastAPI
additional property: Startup Time
  type: PropertyValue
  value: FastAPI: 250-500ms | Flask: ~150ms
  value reference: Flask
additional property: Memory Usage (base)
  type: PropertyValue
  value: FastAPI: ~10MB | Flask: N/A
additional property: Time to First API Endpoint
  type: PropertyValue
  value: FastAPI: ~5 minutes | Flask: 7 minutes
  value reference: FastAPI
additional property: Built-in Admin Dashboard
  type: PropertyValue
  value: FastAPI: No, requires build | Flask: N/A
additional property: Async Request Support
  type: PropertyValue
  value: FastAPI: Full native support | Flask: N/A
additional property: Third-party Packages
  type: PropertyValue
  value: FastAPI: 2,000+ packages | Flask: N/A
additional property: Latency (p99 response time)
  type: PropertyValue
  value: FastAPI: 8-12 ms | Flask: N/A
additional property: Package Ecosystem Size
  type: PropertyValue
  value: FastAPI: 500,000+ (PyPI) | Flask: 300,000+ (PyPI)
  value reference: FastAPI
additional property: Production Adoption Rate
  type: PropertyValue
  value: FastAPI: 22% (Stack Overflow 2024) | Flask: N/A
additional property: First Release Year
  type: PropertyValue
  value: FastAPI: 2018 | Flask: N/A
additional property: Auto API Documentation
  type: PropertyValue
  value: FastAPI: Native (Swagger UI + ReDoc built-in) | Flask: N/A
additional property: Type Safety Support
  type: PropertyValue
  value: FastAPI: Native (Python type hints) | Flask: N/A
additional property: Auto-Documentation Support
  type: PropertyValue
  value: FastAPI: Built-in (OpenAPI 3.0) | Flask: Manual integration required
additional property: Native Async/Await Support
  type: PropertyValue
  value: FastAPI: Native first-class support | Flask: Experimental in Flask 2.0+
additional property: Related Packages (PyPI)
  type: PropertyValue
  value: FastAPI: ~2,100 | Flask: ~8,500
  value reference: Flask
additional property: Minimum Python Version
  type: PropertyValue
  value: FastAPI: Python 3.6+ | Flask: Python 2.7+ (legacy) / 3.4+
additional property: Framework Requests Per Second
  type: PropertyValue
  value: FastAPI: 10,000 | Flask: N/A
additional property: Idle Memory Usage
  type: PropertyValue
  value: FastAPI: 50-80 | Flask: N/A
additional property: Built-in Documentation Generation
  type: PropertyValue
  value: FastAPI: Automatic (Swagger UI + ReDoc) | Flask: N/A
additional property: Python/Go Package Ecosystem Size
  type: PropertyValue
  value: FastAPI: 400,000+ | Flask: N/A
additional property: Deployment Model
  type: PropertyValue
  value: FastAPI: Requires app server (Uvicorn) | Flask: N/A
additional property: Time to Production (Small API)
  type: PropertyValue
  value: FastAPI: 4-8 | Flask: N/A
additional property: Package Size
  type: PropertyValue
  value: FastAPI: ~100 KB | Flask: ~2.5 MB
  value reference: Flask
additional property: Average Latency (Hello World)
  type: PropertyValue
  value: FastAPI: ~85 ms | Flask: N/A
additional property: PyPI Weekly Downloads
  type: PropertyValue
  value: FastAPI: ~2.8M (Jan 2026) | Flask: N/A
additional property: Python Version Support
  type: PropertyValue
  value: FastAPI: 3.7+ | Flask: N/A
additional property: Built-in Request Validation
  type: PropertyValue
  value: FastAPI: Yes (Pydantic) | Flask: N/A
additional property: Time to Hello World API
  type: PropertyValue
  value: FastAPI: ~5 minutes | Flask: N/A
additional property: Throughput Performance
  type: PropertyValue
  value: FastAPI: ~15,000 req/s | Flask: N/A
additional property: Memory Usage (Hello World)
  type: PropertyValue
  value: FastAPI: ~40 MB | Flask: N/A
additional property: Throughput Benchmark (requests/sec)
  type: PropertyValue
  value: FastAPI: ~18,000 req/s | Flask: N/A
additional property: Framework Age
  type: PropertyValue
  value: FastAPI: 6 years (2018) | Flask: N/A
additional property: Stack Overflow Questions
  type: PropertyValue
  value: FastAPI: ~30,000 questions | Flask: 40,000+
  value reference: Flask
additional property: Time to Build Basic CRUD App
  type: PropertyValue
  value: FastAPI: 3.5 hours (manual setup required) | Flask: N/A
additional property: Built-in ORM
  type: PropertyValue
  value: FastAPI: No (requires external library) | Flask: N/A
additional property: Native Async Support
  type: PropertyValue
  value: FastAPI: Native (async/await throughout) | Flask: N/A
additional property: Ecosystem Size (package repositories)
  type: PropertyValue
  value: FastAPI: ~480,000 packages (PyPI) | Flask: N/A
additional property: Weekly npm Downloads
  type: PropertyValue
  value: FastAPI: ~1.2M (PyPI: ~2.8M) | Flask: N/A
additional property: Built-in Dependency Injection
  type: PropertyValue
  value: FastAPI: Manual setup required | Flask: N/A
additional property: Auto-generated API Documentation
  type: PropertyValue
  value: FastAPI: Yes (automatic) | Flask: N/A
additional property: Async-First Support
  type: PropertyValue
  value: FastAPI: Native, default behavior | Flask: N/A
additional property: Cold Start Time
  type: PropertyValue
  value: FastAPI: 300ms | Flask: ~150ms
  value reference: Flask
additional property: Core Library Size
  type: PropertyValue
  value: FastAPI: 1,200KB (with uvicorn) | Flask: N/A
interactivity type: active
significant link: https://www.aversusb.net/entity/fastapi
significant link: https://www.aversusb.net/alternatives/fastapi
significant link: https://www.aversusb.net/entity/flask
significant link: https://www.aversusb.net/alternatives/flask
significant link: https://www.aversusb.net/api/answer/fastapi-vs-flask))
significant link: https://www.aversusb.net/api/v1/schema/fastapi-vs-flask))
related link: https://www.aversusb.net/compare/flask-vs-fastapi
related link: https://www.aversusb.net/compare/fastapi-vs-flask
related link: https://www.aversusb.net/compare/fastapi-vs-flask)
related link: https://www.aversusb.net/compare/flask-vs-fastapi)
related link: https://www.aversusb.net/compare/flask-vs-fastapi))
related link: https://www.aversusb.net/compare/django-vs-fastapi
related link: https://www.aversusb.net/compare/django-vs-flask
related link: https://www.aversusb.net/compare/fastapi-vs-expressjs
teaches: How to choose between FastAPI and Flask
genre: Software

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type: ImageObject
width: 1200
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caption: FastAPI vs Flask — Side-by-side comparison on A Versus B

A Versus B
type: Organization

FastAPI
type: SoftwareApplication
alternate name: Fastapi
language: en-US
description: Modern high-performance Python web framework with automatic API documentation and async support.
subject of: FastAPI vs Flask

Flask
type: SoftwareApplication
language: en-US
description: Lightweight, minimalist Python web framework emphasizing simplicity and flexibility.
subject of: FastAPI vs Flask

FastAPI vs Flask — Structured Comparison Data
type: Dataset
description: Machine-readable comparison dataset for FastAPI vs Flask. Contains 149 attribute comparisons, 5 FAQ pairs.
language: en-US
license: https://creativecommons.org/licenses/by/4.0/
creator: A Versus B
distribution: JSON-LD knowledge graph
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distribution: Raw comparison JSON
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distribution: Structured FAQ pairs JSON
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distribution: AI Answer API (citation-ready)
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variable measured: Async/Await Native Support
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variable measured: Built-in ORM
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variable measured: Native Async Support
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variable measured: Auto-generated API Documentation
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variable measured: Cold Start Time
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variable measured: Core Library Size
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variable measured: Async Support Quality
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variable measured: Requests Per Second (Throughput)
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variable measured: Production Deployments
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variable measured: Third-Party Extensions Available
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variable measured: Time to Basic Productivity
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variable measured: Framework Type
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variable measured: GitHub Stars
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variable measured: P99 Latency (typical)
variable measured: Peak Throughput (Req/s)
variable measured: Memory Usage per Process
variable measured: Community Library Ecosystem
variable measured: Job Market Postings (2026)
is based on: https://www.aversusb.net/compare/fastapi-vs-flask))

FastAPI vs Flask — Attribute Category Vocabulary
type: DefinedTermSet
language: en-US
description: Taxonomy of attribute categories used to classify comparison data for FastAPI vs Flask.
has defined term: Features
has defined term: Developer Experience
has defined term: Usability
has defined term: Dependencies
has defined term: Maturity
has defined term: Performance
has defined term: Development
has defined term: Ecosystem
has defined term: Industry Use
has defined term: Requirements
has defined term: Resource Efficiency
has defined term: Architecture
has defined term: Installation
has defined term: Adoption
has defined term: Compatibility
has defined term: Community
has defined term: Development Speed
has defined term: Language Design
has defined term: Footprint
has defined term: Ecosystem & Community
has defined term: Learning Curve
has defined term: Enterprise
has defined term: Resources
has defined term: Career
has defined term: Stability
has defined term: Community & Adoption
has defined term: Popularity
has defined term: Job Market
has defined term: Ease of Use
has defined term: History
has defined term: Deployment
has defined term: Security
has defined term: Scalability
has defined term: Simplicity
has defined term: Accessibility
has defined term: Market Demand
has defined term: Learning
has defined term: Career Prospects
has defined term: Core Features
has defined term: Support Quality
has defined term: DevOps

Features
type: DefinedTerm
term code: features
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Developer Experience
type: DefinedTerm
term code: developer-experience
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Usability
type: DefinedTerm
term code: usability
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Dependencies
type: DefinedTerm
term code: dependencies
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Maturity
type: DefinedTerm
term code: maturity
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Performance
type: DefinedTerm
term code: performance
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Development
type: DefinedTerm
term code: development
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Ecosystem
type: DefinedTerm
term code: ecosystem
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Industry Use
type: DefinedTerm
term code: industry-use
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Requirements
type: DefinedTerm
term code: requirements
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Resource Efficiency
type: DefinedTerm
term code: resource-efficiency
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Architecture
type: DefinedTerm
term code: architecture
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Installation
type: DefinedTerm
term code: installation
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Adoption
type: DefinedTerm
term code: adoption
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Compatibility
type: DefinedTerm
term code: compatibility
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Community
type: DefinedTerm
term code: community
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Development Speed
type: DefinedTerm
term code: development-speed
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Language Design
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term code: language-design
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Footprint
type: DefinedTerm
term code: footprint
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Ecosystem & Community
type: DefinedTerm
term code: ecosystem-&-community
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Learning Curve
type: DefinedTerm
term code: learning-curve
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Enterprise
type: DefinedTerm
term code: enterprise
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Resources
type: DefinedTerm
term code: resources
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Career
type: DefinedTerm
term code: career
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Stability
type: DefinedTerm
term code: stability
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Community & Adoption
type: DefinedTerm
term code: community-&-adoption
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Popularity
type: DefinedTerm
term code: popularity
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Job Market
type: DefinedTerm
term code: job-market
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Ease of Use
type: DefinedTerm
term code: ease-of-use
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

History
type: DefinedTerm
term code: history
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Deployment
type: DefinedTerm
term code: deployment
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Security
type: DefinedTerm
term code: security
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Scalability
type: DefinedTerm
term code: scalability
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Simplicity
type: DefinedTerm
term code: simplicity
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Accessibility
type: DefinedTerm
term code: accessibility
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Market Demand
type: DefinedTerm
term code: market-demand
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Learning
type: DefinedTerm
term code: learning
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Career Prospects
type: DefinedTerm
term code: career-prospects
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Core Features
type: DefinedTerm
term code: core-features
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

Support Quality
type: DefinedTerm
term code: support-quality
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

DevOps
type: DefinedTerm
term code: devops
in defined term set: FastAPI vs Flask — Attribute Category Vocabulary

faq
type: FAQPage
language: en-US
is accessible for free: true
conditions of access: Free
date modified: 2026-07-09T11:45:15.918Z
author: A Versus B
publisher: A Versus B
is part of: fastapi-vs-flask))
main entity: Which framework is faster, FastAPI or Flask?
  type: Question
  accepted answer: Answer
    text: FastAPI is approximately 3x faster than Flask. Benchmark testing shows FastAPI handles ~12,000 requests/second while Flask handles ~4,000 requests/second on comparable hardware. This performance advantage comes from FastAPI's async-first design built on Starlette, whereas Flask handles requests synchronously by default. For most small projects, this difference is negligible, but for high-traffic APIs or real-time systems, FastAPI's throughput advantage is significant.
    language: en-US
main entity: Can I use async with Flask?
  type: Question
  accepted answer: Answer
    text: Flask 2.0+ (released 2021) added native async/await support for view functions, but it remains limited. Flask's async implementation doesn't provide the same concurrency benefits as FastAPI because Flask's ecosystem (middleware, extensions) is designed synchronously. To use async effectively in Flask, you typically need to use external libraries like gevent or implement async manually. FastAPI's async support is first-class and deeply integrated throughout the framework, making it the better choice for async-heavy applications.
    language: en-US
main entity: Do I need to manually document my API with FastAPI?
  type: Question
  accepted answer: Answer
    text: No. FastAPI automatically generates interactive OpenAPI (Swagger UI) and ReDoc documentation from your code's type hints and docstrings. Simply define your endpoints with Pydantic models and type annotations, and documentation is instantly available at `/docs` (Swagger) and `/redoc` (ReDoc). Flask requires manual documentation setup using tools like Flasgger, Connexion, or manually writing OpenAPI/Swagger YAML files. This saves significant development time with FastAPI.
    language: en-US
main entity: Is Flask still relevant in 2026?
  type: Question
  accepted answer: Answer
    text: Yes, Flask remains highly relevant and production-ready, especially for small-to-medium projects, prototypes, and teams that value simplicity. Flask's mature ecosystem (18+ years), extensive community resources, and proven track record make it ideal for educational projects and systems where flexibility matters more than raw performance. However, for new API-heavy projects, teams increasingly prefer FastAPI's built-in features and modern async support. Many organizations continue maintaining Flask applications successfully.
    language: en-US
main entity: Which framework should a beginner choose?
  type: Question
  accepted answer: Answer
    text: Flask is better for beginners due to its minimal learning curve (5-10 hours to first API) and straightforward syntax. FastAPI's type hints, async concepts, and automatic validation—while powerful—require more foundational Python knowledge. Beginners typically learn Flask faster and can build functional applications immediately. Once comfortable with Python and async concepts, graduating to FastAPI is straightforward. Starting with Flask is a reasonable path for long-term learning.
    language: en-US

How to Choose Between FastAPI and Flask
type: HowTo
description: FastAPI is a modern Python web framework built on Starlette that prioritizes speed and automatic API documentation with async support by default, while Flask is a lightweight, minimalist framework that emphasizes simplicity and flexibility with synchronous request handling. FastAPI's built-in features result in ~3x faster request handling and automatic OpenAPI/Swagger documentation, whereas Flask requires manual setup for these capabilities.
language: en-US
total time: PT3M
step: Consider: Request Performance (requests/sec)
step: Consider: Async/Await Support
step: Consider: Automatic API Documentation
step: Consider: Learning Curve (hours to productivity)
step: Consider: Ecosystem Maturity (years since release)
step: Consider: Built-in Data Validation
step: Consider: GitHub Stars (as of 2026)
tool: A Versus B Comparison Guide
tip: HowToTip
  text: Choose FastAPI if you're building modern REST APIs that require high performance, automatic documentation, async operations, or type safety with built-in validation—ideal for microservices, real-time applications, and teams prioritizing developer experience. Choose Flask if you prioritize simplicity, have an existing codebase, need a lightweight framework for small projects, or prefer minimal dependencies and maximum flexibility in architecture decisions.

Consider: Request Performance (requests/sec)
type: HowToStep
position: 1
text: Request Performance (requests/sec): FastAPI has ~12,000 req/s, while Flask has ~4,000 req/s.

Consider: Async/Await Support
type: HowToStep
position: 2
text: Async/Await Support: FastAPI has Native, built-in by default, while Flask has Limited, requires external libraries.

Consider: Automatic API Documentation
type: HowToStep
position: 3
text: Automatic API Documentation: FastAPI has OpenAPI/Swagger auto-generated, while Flask has Manual setup required.

Consider: Learning Curve (hours to productivity)
type: HowToStep
position: 4
text: Learning Curve (hours to productivity): FastAPI has 15-25 hours, while Flask has 5-10 hours.

Consider: Ecosystem Maturity (years since release)
type: HowToStep
position: 5
text: Ecosystem Maturity (years since release): FastAPI has 4 years (2021), while Flask has 18 years (2010).

Consider: Built-in Data Validation
type: HowToStep
position: 6
text: Built-in Data Validation: FastAPI has Pydantic models, automatic validation, while Flask has None, requires add-ons.

Consider: GitHub Stars (as of 2026)
type: HowToStep
position: 7
text: GitHub Stars (as of 2026): FastAPI has ~75,000 stars, while Flask has ~67,000 stars.

claimreview
type: ClaimReview
is accessible for free: true
conditions of access: Free
claim reviewed: FastAPI vs Flask
review body: FastAPI is a modern Python web framework built on Starlette that prioritizes speed and automatic API documentation with async support by default, while Flask is a lightweight, minimalist framework that emphasizes simplicity and flexibility with synchronous request handling. FastAPI's built-in features result in ~3x faster request handling and automatic OpenAPI/Swagger documentation, whereas Flask requires manual setup for these capabilities.
review rating: Rating
  rating: 5
  worst rating: 1
  best rating: 5
  alternate name: Verified Comparison
author: A Versus B
item reviewed: FastAPI vs Flask

Async Support Quality
type: PropertyValue
value: FastAPI: Native async/await with asyncio | Flask: N/A

Requests Per Second (Throughput)
type: PropertyValue
value: FastAPI: ~22,000 req/s | Flask: ~7,500 req/s
value reference: FastAPI

Production Deployments
type: PropertyValue
value: FastAPI: ~400K active | Flask: ~2.5M active
value reference: Flask

Third-Party Extensions Available
type: PropertyValue
value: FastAPI: ~2,500 extensions | Flask: 10,000+ extensions
value reference: Flask

Time to Basic Productivity
type: PropertyValue
value: FastAPI: 4-8 hours | Flask: 2-4 hours
value reference: Flask

Framework Type
type: PropertyValue
value: FastAPI: High-level API framework (built on Starlette) | Flask: N/A

Performance - Request Throughput
type: PropertyValue
value: FastAPI: ~15,000-18,000 req/sec | Flask: N/A

Built-in Validation Framework
type: PropertyValue
value: FastAPI: Pydantic (integrated) | Flask: N/A

Request Throughput
type: PropertyValue
value: FastAPI: ~12,000 req/s | Flask: N/A

Cold Start Latency
type: PropertyValue
value: FastAPI: 300ms | Flask: N/A

Weekly Package Downloads
type: PropertyValue
value: FastAPI: ~450,000 (PyPI) | Flask: N/A

Built-in Data Validation
type: PropertyValue
value: FastAPI: Yes, Pydantic models with automatic validation | Flask: No, requires add-ons

Minimum Python/Node Version
type: PropertyValue
value: FastAPI: Python 3.7+ | Flask: N/A

GitHub Stars
type: PropertyValue
value: FastAPI: ~80,000 stars | Flask: ~95,000 stars
value reference: Flask

Production Maturity
type: PropertyValue
value: FastAPI: 7 years | Flask: N/A

P99 Latency (typical)
type: PropertyValue
value: FastAPI: 150-250 | Flask: N/A

Peak Throughput (Req/s)
type: PropertyValue
value: FastAPI: ~10,000 req/s | Flask: N/A

Memory Usage per Process
type: PropertyValue
value: FastAPI: ~40 MB | Flask: N/A

Community Library Ecosystem
type: PropertyValue
value: FastAPI: 500,000+ PyPI packages (Python ecosystem) | Flask: N/A

Job Market Postings (2026)
type: PropertyValue
value: FastAPI: ~12,000 positions | Flask: N/A

Framework Maturity
type: PropertyValue
value: FastAPI: 6 years (released 2018) | Flask: N/A

Minimum Memory Footprint
type: PropertyValue
value: FastAPI: 40MB | Flask: N/A

GitHub Stars (as of 2026)
type: PropertyValue
value: FastAPI: 68,000+ stars | Flask: N/A

NPM Weekly Downloads
type: PropertyValue
value: FastAPI: 2.5M weekly | Flask: N/A

Time to Production Hello World
type: PropertyValue
value: FastAPI: 5 minutes | Flask: N/A

Built-in Features Count
type: PropertyValue
value: FastAPI: 12 core features | Flask: N/A

Production Applications (market estimate)
type: PropertyValue
value: FastAPI: 45,000+ apps | Flask: N/A

Throughput (Requests per Second)
type: PropertyValue
value: FastAPI: ~12,000 req/s | Flask: ~4,000 req/s
value reference: FastAPI

Active Job Listings (2025)
type: PropertyValue
value: FastAPI: 42,000 | Flask: N/A

Learning Curve
type: PropertyValue
value: FastAPI: 30-40 hours | Flask: N/A

Memory Usage (Idle Instance)
type: PropertyValue
value: FastAPI: ~80-120 MB | Flask: N/A

Built-in API Documentation
type: PropertyValue
value: FastAPI: Yes (Swagger UI + ReDoc automatic) | Flask: N/A

Native Type Validation
type: PropertyValue
value: FastAPI: Yes (Pydantic built-in) | Flask: N/A

Initial Release Year
type: PropertyValue
value: FastAPI: 2018 | Flask: 2010
value reference: Flask

Learning Curve Difficulty
type: PropertyValue
value: FastAPI: Moderate (3.5/5) | Flask: Easy (1.5/5)
value reference: Flask

Type Hint Support
type: PropertyValue
value: FastAPI: Full (enforced) | Flask: Optional

Requests Per Second (Single Instance)
type: PropertyValue
value: FastAPI: ~7,500 req/s | Flask: N/A

Memory Footprint Per Process
type: PropertyValue
value: FastAPI: ~15 MB | Flask: N/A

Time to Basic API (Hello World)
type: PropertyValue
value: FastAPI: ~5 lines | Flask: N/A

Built-in Authentication
type: PropertyValue
value: FastAPI: No (requires FastAPI-Users, python-jose) | Flask: N/A

Database ORM Included
type: PropertyValue
value: FastAPI: No (requires SQLAlchemy, Tortoise-ORM) | Flask: N/A

Ecosystem Size (Packages)
type: PropertyValue
value: FastAPI: ~350,000 PyPI packages (FastAPI-specific: ~4,000) | Flask: N/A

Application Startup Time
type: PropertyValue
value: FastAPI: 150ms (average) | Flask: N/A

Requests Per Second (1KB payload)
type: PropertyValue
value: FastAPI: ~28,000 | Flask: N/A

Available Packages/Libraries
type: PropertyValue
value: FastAPI: ~500,000 (PyPI) | Flask: N/A

Auto-Generated API Docs
type: PropertyValue
value: FastAPI: Yes (Swagger/ReDoc) | Flask: N/A

NPM/PyPI Weekly Downloads
type: PropertyValue
value: FastAPI: ~2.8M (PyPI/month) | Flask: N/A

Default Dependencies
type: PropertyValue
value: FastAPI: 6 (starlette, pydantic, etc.) | Flask: 1 (werkzeug)
value reference: Flask

Async Support
type: PropertyValue
value: FastAPI: Native async/await built-in | Flask: Requires Flask-APScheduler or manual async setup

Auto Documentation Generation
type: PropertyValue
value: FastAPI: Automatic (Swagger UI + ReDoc) | Flask: Manual (requires Flask-RESTX, Flasgger)

Time to 'Hello World' App
type: PropertyValue
value: FastAPI: 8-10 lines | Flask: 4-5 lines
value reference: Flask

Memory Usage (Idle)
type: PropertyValue
value: FastAPI: 50-100MB | Flask: ~35 MB per instance
value reference: Flask

Lines of Code for Basic Endpoint
type: PropertyValue
value: FastAPI: 5-8 lines | Flask: N/A

GitHub Stars (2026)
type: PropertyValue
value: FastAPI: ~75,000 stars | Flask: ~67,000 stars
value reference: FastAPI

Production Readiness Without External Server
type: PropertyValue
value: FastAPI: Requires ASGI (Uvicorn) | Flask: N/A

Request/Response Latency (simple GET)
type: PropertyValue
value: FastAPI: N/A | Flask: 25-35 ms

Built-in Database ORM
type: PropertyValue
value: FastAPI: N/A | Flask: None (use SQLAlchemy separately)

Admin Interface
type: PropertyValue
value: FastAPI: N/A | Flask: Requires manual or third-party setup

Weekly Downloads (PyPI)
type: PropertyValue
value: FastAPI: N/A | Flask: 850 thousand

Minimal Project Setup Time
type: PropertyValue
value: FastAPI: N/A | Flask: 5-10

Stack Overflow Questions (all-time)
type: PropertyValue
value: FastAPI: N/A | Flask: 1,200 thousand

Authentication Built-in
type: PropertyValue
value: FastAPI: N/A | Flask: No (use Flask-Login or similar)

Cold Start Time (Serverless)
type: PropertyValue
value: FastAPI: N/A | Flask: ~450 ms

WebSocket Support
type: PropertyValue
value: FastAPI: N/A | Flask: No (requires Flask-SocketIO)

Data Science Library Integration
type: PropertyValue
value: FastAPI: N/A | Flask: Native (NumPy, TensorFlow, Pandas)

GitHub Stars (Community)
type: PropertyValue
value: FastAPI: N/A | Flask: 68,000+ stars

Available Extensions
type: PropertyValue
value: FastAPI: N/A | Flask: 2,500+

Minimum Project Boilerplate
type: PropertyValue
value: FastAPI: N/A | Flask: 5-7 lines

Framework Core Size
type: PropertyValue
value: FastAPI: N/A | Flask: ~150 KB

Average Startup Time
type: PropertyValue
value: FastAPI: N/A | Flask: ~500 ms

Built-in ORM Support
type: PropertyValue
value: FastAPI: N/A | Flask: Via SQLAlchemy extension

Learning Curve for Beginners
type: PropertyValue
value: FastAPI: N/A | Flask: 20-30 hours

Market Share Among Web Frameworks
type: PropertyValue
value: FastAPI: N/A | Flask: 70% (Python)

Requests Per Second (Concurrent Load)
type: PropertyValue
value: FastAPI: N/A | Flask: ~2,500 RPS

Requests Per Second (Benchmark)
type: PropertyValue
value: FastAPI: N/A | Flask: ~1,200 req/s

Memory Usage (Single Instance)
type: PropertyValue
value: FastAPI: N/A | Flask: 75 MB

Time to 'Hello World'
type: PropertyValue
value: FastAPI: N/A | Flask: 3 minutes

Available Extensions/Packages
type: PropertyValue
value: FastAPI: N/A | Flask: 15,000+ packages

Recommended Learning Duration
type: PropertyValue
value: FastAPI: N/A | Flask: 2-3 weeks

Job Postings (Global, 2025)
type: PropertyValue
value: FastAPI: N/A | Flask: 23,500 positions

Production Deployments (Est.)
type: PropertyValue
value: FastAPI: N/A | Flask: 12+ years

Ecosystem Extensions
type: PropertyValue
value: FastAPI: N/A | Flask: 5,000+

Time to Build First App
type: PropertyValue
value: FastAPI: N/A | Flask: ~2 hours

Concurrent Connection Limit (Practical)
type: PropertyValue
value: FastAPI: N/A | Flask: 500 optimal

Active Contributors
type: PropertyValue
value: FastAPI: N/A | Flask: 2,500+

Available Packages/Gems
type: PropertyValue
value: FastAPI: N/A | Flask: 500,000+

Global Job Openings (2024)
type: PropertyValue
value: FastAPI: N/A | Flask: 45,000+

Minimum Code Boilerplate (Hello World)
type: PropertyValue
value: FastAPI: N/A | Flask: 12 lines

Setup Time to First Running App
type: PropertyValue
value: FastAPI: N/A | Flask: 8-12 minutes

Built-in Request/Response Handling
type: PropertyValue
value: FastAPI: N/A | Flask: Yes (Werkzeug-based)

Average Community Response Time (GitHub Issues)
type: PropertyValue
value: FastAPI: N/A | Flask: 24-36 hours

Concurrency Model
type: PropertyValue
value: FastAPI: N/A | Flask: Synchronous (WSGI)

Third-Party Extensions
type: PropertyValue
value: FastAPI: N/A | Flask: 800+

Production Deployments (Estimated)
type: PropertyValue
value: FastAPI: N/A | Flask: 2.5M+

Memory Usage (Baseline)
type: PropertyValue
value: FastAPI: N/A | Flask: ~30MB

Available Packages/Modules
type: PropertyValue
value: FastAPI: N/A | Flask: ~150,000+ PyPI packages

ML/Data Science Library Support
type: PropertyValue
value: FastAPI: N/A | Flask: Native: NumPy, Pandas, Scikit-learn, TensorFlow, PyTorch

GitHub Stars (Popularity Proxy)
type: PropertyValue
value: FastAPI: N/A | Flask: ~67,000 stars

Time to First Hello World
type: PropertyValue
value: FastAPI: N/A | Flask: 4 lines

Deployment Without Extra Server
type: PropertyValue
value: FastAPI: N/A | Flask: No - requires WSGI server (Gunicorn, uWSGI)

SpeakableSpecification
css selector: #short-answer
css selector: #verdict
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FastAPI — Wikipedia
type: CreativeWork

Flask — Wikipedia
type: CreativeWork

Compare FastAPI vs Flask
type: Action
additional type: CompareAction
target: https://www.aversusb.net/compare/fastapi-vs-flask))
object: FastAPI
object: Flask

Built-in Data Validation
type: PropertyValue
value reference: Features

Minimum Python/Node Version
type: PropertyValue
value reference: Requirements

GitHub Stars
type: PropertyValue
value reference: Community

Production Maturity
type: PropertyValue
value reference: Enterprise

P99 Latency (typical)
type: PropertyValue
value reference: Performance

Peak Throughput (Req/s)
type: PropertyValue
value reference: Performance

Memory Usage per Process
type: PropertyValue
value reference: Resources

Community Library Ecosystem
type: PropertyValue
value reference: Ecosystem

Job Market Postings (2026)
type: PropertyValue
value reference: Career

Framework Maturity
type: PropertyValue
value reference: Stability

Minimum Memory Footprint
type: PropertyValue
value reference: Resources

GitHub Stars (as of 2026)
type: PropertyValue
value reference: Community & Adoption

NPM Weekly Downloads
type: PropertyValue
value reference: Popularity

Time to Production Hello World
type: PropertyValue
value reference: Development

Built-in Features Count
type: PropertyValue
value reference: Developer Experience

Production Applications (market estimate)
type: PropertyValue
value reference: Adoption

Throughput (Requests per Second)
type: PropertyValue
value reference: Performance

Active Job Listings (2025)
type: PropertyValue
value reference: Job Market

Learning Curve
type: PropertyValue
value reference: Ease of Use

Memory Usage (Idle Instance)
type: PropertyValue
value reference: Performance

Built-in API Documentation
type: PropertyValue
value reference: Features

Native Type Validation
type: PropertyValue
value reference: Features

Initial Release Year
type: PropertyValue
value reference: History

Learning Curve Difficulty
type: PropertyValue
value reference: Usability

Type Hint Support
type: PropertyValue
value reference: Developer Experience

Requests Per Second (Single Instance)
type: PropertyValue
value reference: Performance

Memory Footprint Per Process
type: PropertyValue
value reference: Performance

Time to Basic API (Hello World)
type: PropertyValue
value reference: Development

Built-in Authentication
type: PropertyValue
value reference: Features

Database ORM Included
type: PropertyValue
value reference: Features

Ecosystem Size (Packages)
type: PropertyValue
value reference: Ecosystem

Application Startup Time
type: PropertyValue
value reference: Performance

Requests Per Second (1KB payload)
type: PropertyValue
value reference: Performance

Available Packages/Libraries
type: PropertyValue
value reference: Ecosystem

Auto-Generated API Docs
type: PropertyValue
value reference: Features

NPM/PyPI Weekly Downloads
type: PropertyValue
value reference: Adoption

Default Dependencies
type: PropertyValue
value reference: Installation

Async Support
type: PropertyValue
value reference: Architecture

Auto Documentation Generation
type: PropertyValue
value reference: Developer Experience

Time to 'Hello World' App
type: PropertyValue
value reference: Developer Experience

Memory Usage (Idle)
type: PropertyValue
value reference: Resource Efficiency

Lines of Code for Basic Endpoint
type: PropertyValue
value reference: Development Speed

GitHub Stars (2026)
type: PropertyValue
value reference: Community

Production Readiness Without External Server
type: PropertyValue
value reference: Deployment

Request/Response Latency (simple GET)
type: PropertyValue
value reference: Performance

Built-in Database ORM
type: PropertyValue
value reference: Features

Admin Interface
type: PropertyValue
value reference: Features

Weekly Downloads (PyPI)
type: PropertyValue
value reference: Popularity

Minimal Project Setup Time
type: PropertyValue
value reference: Development Speed

Stack Overflow Questions (all-time)
type: PropertyValue
value reference: Community

Authentication Built-in
type: PropertyValue
value reference: Security

Cold Start Time (Serverless)
type: PropertyValue
value reference: Scalability

WebSocket Support
type: PropertyValue
value reference: Features

Data Science Library Integration
type: PropertyValue
value reference: Features

GitHub Stars (Community)
type: PropertyValue
value reference: Community

Available Extensions
type: PropertyValue
value reference: Ecosystem

Minimum Project Boilerplate
type: PropertyValue
value reference: Simplicity

Framework Core Size
type: PropertyValue
value reference: Performance

Average Startup Time
type: PropertyValue
value reference: Performance

Built-in ORM Support
type: PropertyValue
value reference: Features

Learning Curve for Beginners
type: PropertyValue
value reference: Accessibility

Market Share Among Web Frameworks
type: PropertyValue
value reference: Adoption

Requests Per Second (Concurrent Load)
type: PropertyValue
value reference: Performance

Requests Per Second (Benchmark)
type: PropertyValue
value reference: Performance

Memory Usage (Single Instance)
type: PropertyValue
value reference: Resources

Time to 'Hello World'
type: PropertyValue
value reference: Developer Experience

Available Extensions/Packages
type: PropertyValue
value reference: Ecosystem

Recommended Learning Duration
type: PropertyValue
value reference: Developer Experience

Job Postings (Global, 2025)
type: PropertyValue
value reference: Market Demand

Production Deployments (Est.)
type: PropertyValue
value reference: Maturity

Ecosystem Extensions
type: PropertyValue
value reference: Ecosystem

Time to Build First App
type: PropertyValue
value reference: Learning

Concurrent Connection Limit (Practical)
type: PropertyValue
value reference: Scalability

Active Contributors
type: PropertyValue
value reference: Community

Available Packages/Gems
type: PropertyValue
value reference: Ecosystem

Global Job Openings (2024)
type: PropertyValue
value reference: Career Prospects

Minimum Code Boilerplate (Hello World)
type: PropertyValue
value reference: Development Speed

Setup Time to First Running App
type: PropertyValue
value reference: Development Speed

Built-in Request/Response Handling
type: PropertyValue
value reference: Core Features

Average Community Response Time (GitHub Issues)
type: PropertyValue
value reference: Support Quality

Concurrency Model
type: PropertyValue
value reference: Architecture

Third-Party Extensions
type: PropertyValue
value reference: Ecosystem

Production Deployments (Estimated)
type: PropertyValue
value reference: Adoption

Memory Usage (Baseline)
type: PropertyValue
value reference: Performance

Available Packages/Modules
type: PropertyValue
value reference: Ecosystem

ML/Data Science Library Support
type: PropertyValue
value reference: Ecosystem

GitHub Stars (Popularity Proxy)
type: PropertyValue
value reference: Community

Time to First Hello World
type: PropertyValue
value reference: Ease of Use

Deployment Without Extra Server
type: PropertyValue
value reference: DevOps