Available worldwide
What is FastAPI?
Modern Python framework for building APIs with automatic documentation based on OpenAPI and JSON Schema standards.
What FastAPI does
The capabilities that matter for web frameworks, normalised so it lines up with every alternative. “-” means we haven't confirmed it, not that it's missing.
- Rendering model
- -
- File-based routing
- -
- Language
- Python
- Server components
- -
- Streaming SSR
- -
- Built-in API / backend routes
- ✓
- First-class TypeScript
- -
- Fast refresh / HMR
- -
- Edge runtime support
- -
Platform & deployment
Independently observed- CLI
- Cloud / SaaS
- Self-hosted
FastAPI FAQ
Common questions about FastAPI, answered from independent, dated evidence.
What is FastAPI and what is it primarily used for?
FastAPI is a modern Python framework for building REST APIs and web services. It is built on top of Starlette for web functionality and Pydantic for data validation, combining these components with Python type hints to enable automatic API documentation, data validation, and fast development cycles.
Source: https://fastapi.tiangolo.com
What programming language is FastAPI built on and what are its core dependencies?
FastAPI is a Python framework that relies on Starlette for HTTP handling and async support, and Pydantic for data validation and serialization. It leverages Python's native type hints as a central feature to drive both validation and automatic interactive API documentation generation.
Source: https://fastapi.tiangolo.com
Is FastAPI open source and what is its pricing model?
FastAPI is completely open source and free, distributed under the MIT license with no cost to use or modify. The creators offer an optional commercial service called FastAPI Cloud for managed deployment and hosting, but the core framework incurs no licensing fees.
Source: https://fastapi.tiangolo.com
How does FastAPI's performance compare to other Python web frameworks?
FastAPI is one of the fastest Python web frameworks, with benchmarks showing performance on par with Node.js and Go-based APIs. This speed stems from its async/await capabilities and reliance on highly optimized underlying libraries like Starlette and Pydantic.
Source: https://fastapi.tiangolo.com
What ASGI server should I use to deploy FastAPI, and what are the typical deployment models?
Uvicorn is the standard ASGI server for FastAPI, run via the fastapi run command or uvicorn CLI. Deployment typically involves running Uvicorn with multiple worker processes for concurrency, containerizing with Docker for cloud platforms, or using managed services that automatically handle scaling and reverse proxying.
Does FastAPI support real-time communication and asynchronous patterns?
FastAPI has built-in support for WebSockets enabling real-time bidirectional communication, Server-Sent Events for server-to-client streaming, and background tasks for asynchronous processing. All of these features are natively integrated without requiring additional extensions.
What authentication and security capabilities does FastAPI provide out of the box?
FastAPI includes built-in support for OAuth2 with JSON Web Tokens (JWT), HTTP Basic Authentication, password hashing utilities, bearer token validation, and Cross-Origin Resource Sharing (CORS) configuration. These security patterns are designed to be straightforward to implement for common use cases.
What common integrations and databases does FastAPI support?
FastAPI integrates with SQL relational databases via standard ORMs, supports form data and file uploads, includes middleware patterns, and can mount alongside WSGI applications like Flask or Django. It also provides Jinja2 template support, dependency injection for complex patterns, and auto-generation of client SDKs from your API.
FastAPI alternatives
Other web frameworks we track, ranked by the same independent score.
The Vioscale score: one lens on the evidence
Not user reviews and not a paid placement: a confidence-weighted blend of the independent signals below (adoption, activity, security posture, and more), which you can sort and re-weight yourself. Vendors can correct their listing but can never move their rank, and stars are weighted low as a vanity metric. It is one way to read the evidence for FastAPI, not the verdict.
| Signal | Score | Weight | Contribution | Evidence |
|---|---|---|---|---|
| Package Downloads | 88 | 0.20 | 17.7 | ✓ |
| Github Activity | 73 | 0.14 | 10.1 | ✓ |
| Stackoverflow Activity | 80 | 0.09 | 7.4 | ✓ |
| Release Cadence | 92 | 0.08 | 7.1 | ✓ |
| Capabilities | 29 | 0.12 | 3.6 | ✓ |
| Github Stars | 92 | 0.04 | 3.5 | ✓ |
| Reliability | 50 | 0.06 | 3.1 | ✓ |
| Price Level | 0 | 0.05 | 0.0 | - |
| Integrations | 0 | 0.06 | 0.0 | - |
| Security Posture | 0 | 0.10 | 0.0 | - |
| Pricing Transparency | 0 | 0.06 | 0.0 | - |
Computed . Re-weight it by intent, or see the full method.
All data & sourcesshow ↓
Every value we hold, with its source, retrieval date, and confidence. This is the evidence behind the score: don't trust it, verify it.
Activity
| Attribute | Value | Evidence |
|---|---|---|
| Commits last 30d | 210 | mediumsource · 2026-07-30 · 70% |
Adoption
Content
| Attribute | Value | Evidence |
|---|---|---|
| Faq | [{"answer":"FastAPI is a modern Python framework for building REST APIs and web services. It is built on top of Starlette for web functionality and Pydantic for data validation, combining these components with Python type hints to enable automatic API documentation, data validation, and fast development cycles.","source":"https://fastapi.tiangolo.com","question":"What is FastAPI and what is it primarily used for?","confidence":0.95},{"answer":"FastAPI is a Python framework that relies on Starlette for HTTP handling and async support, and Pydantic for data validation and serialization. It leverages Python's native type hints as a central feature to drive both validation and automatic interactive API documentation generation.","source":"https://fastapi.tiangolo.com","question":"What programming language is FastAPI built on and what are its core dependencies?","confidence":0.95},{"answer":"FastAPI is completely open source and free, distributed under the MIT license with no cost to use or modify. The creators offer an optional commercial service called FastAPI Cloud for managed deployment and hosting, but the core framework incurs no licensing fees.","source":"https://fastapi.tiangolo.com","question":"Is FastAPI open source and what is its pricing model?","confidence":0.95},{"answer":"FastAPI is one of the fastest Python web frameworks, with benchmarks showing performance on par with Node.js and Go-based APIs. This speed stems from its async/await capabilities and reliance on highly optimized underlying libraries like Starlette and Pydantic.","source":"https://fastapi.tiangolo.com","question":"How does FastAPI's performance compare to other Python web frameworks?","confidence":0.92},{"answer":"Uvicorn is the standard ASGI server for FastAPI, run via the fastapi run command or uvicorn CLI. Deployment typically involves running Uvicorn with multiple worker processes for concurrency, containerizing with Docker for cloud platforms, or using managed services that automatically handle scaling and reverse proxying.","source":"https://fastapi.tiangolo.com/deployment/concepts/","question":"What ASGI server should I use to deploy FastAPI, and what are the typical deployment models?","confidence":0.93},{"answer":"FastAPI has built-in support for WebSockets enabling real-time bidirectional communication, Server-Sent Events for server-to-client streaming, and background tasks for asynchronous processing. All of these features are natively integrated without requiring additional extensions.","source":"https://fastapi.tiangolo.com/advanced/","question":"Does FastAPI support real-time communication and asynchronous patterns?","confidence":0.94},{"answer":"FastAPI includes built-in support for OAuth2 with JSON Web Tokens (JWT), HTTP Basic Authentication, password hashing utilities, bearer token validation, and Cross-Origin Resource Sharing (CORS) configuration. These security patterns are designed to be straightforward to implement for common use cases.","source":"https://fastapi.tiangolo.com/advanced/","question":"What authentication and security capabilities does FastAPI provide out of the box?","confidence":0.93},{"answer":"FastAPI integrates with SQL relational databases via standard ORMs, supports form data and file uploads, includes middleware patterns, and can mount alongside WSGI applications like Flask or Django. It also provides Jinja2 template support, dependency injection for complex patterns, and auto-generation of client SDKs from your API.","source":"https://fastapi.tiangolo.com/advanced/","question":"What common integrations and databases does FastAPI support?","confidence":0.92}] | highsource · 2026-07-30 · 94% |
Features
| Attribute | Value | Evidence |
|---|---|---|
| Capabilities | {"language":"Python","api_routes":true} | mediumsource · 2026-08-05 · 60% |
Language
| Attribute | Value | Evidence |
|---|---|---|
| Primary | Python | highsource · 2026-07-30 · 90% |
License
| Attribute | Value | Evidence |
|---|---|---|
| Spdx | MIT | highsource · 2026-07-30 · 95% |
Market
| Attribute | Value | Evidence |
|---|---|---|
| Availability | {"source":"https://fastapi.tiangolo.com","hqCountry":"ES","confidence":0.95,"primaryMarkets":[],"availabilityScope":"global","availableCountries":[],"notAvailableCountries":[]} | highsource · 2026-07-30 · 95% |
Pricing
| Attribute | Value | Evidence |
|---|---|---|
| Model | commercial | mediumsource · 2026-08-05 · 60% |
Release
| Attribute | Value | Evidence |
|---|---|---|
| Cadence days | 14 | mediumsource · 2026-07-30 · 70% |
Reliability
| Attribute | Value | Evidence |
|---|---|---|
| Status page | Yes | mediumsource · 2026-08-05 · 60% |