How to handle file uploads with APIFlask?

Use Flask's request.files in combination with APIFlask decorators; the documentation provides examples for integrating multipart form data validation.

APIFlask vs FastAPI: which one should I use?

Choose APIFlask if you need Flask compatibility and incremental adoption; FastAPI is better for native async, performance, and out-of-the-box features like dependency injection.

Can I use APIFlask with SQLAlchemy or other ORMs?

Yes, APIFlask is ORM-agnostic and works seamlessly with SQLAlchemy, Django ORM, or any database layer, as it focuses on API logic without dictating data persistence.

How to add JWT authentication to APIFlask?

Integrate with Flask extensions like Flask-JWT-Extended or Flask-HTTPAuth; APIFlask's documentation includes guides for securing endpoints with these tools.

Is APIFlask production-ready for large-scale APIs?

Yes, it's stable and used in production, but consider performance testing and async needs; for high-scale, async-native frameworks might be more suitable.

How to migrate from Flask to APIFlask without breaking changes?

Replace Flask with APIFlask in imports, use APIBlueprint for blueprints, and gradually adopt decorators; the migration guide details minimal code changes.

APIFlask

MITPython3.1.0

A lightweight Python web API framework built on Flask with automatic OpenAPI documentation and request/response handling.

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1.1k stars140 forks0 contributors

What is APIFlask?

APIFlask is a lightweight Python web API framework built on top of Flask. It simplifies API development by adding declarative decorators for request validation and response serialization, and automatically generates OpenAPI documentation. It solves the problem of writing repetitive boilerplate code for input/output handling and documentation in Flask-based APIs.

Target Audience

Python developers building RESTful APIs with Flask who want automatic OpenAPI documentation, reduced boilerplate, and a more structured approach without leaving the Flask ecosystem.

Value Proposition

Developers choose APIFlask because it offers a Flask-like experience with added API-specific conveniences, supports both marshmallow and Pydantic for validation, and generates interactive documentation automatically—all while remaining 100% compatible with existing Flask extensions and patterns.

Overview

A lightweight Python web API framework.

Use Cases

Best For

Building RESTful APIs with automatic OpenAPI/Swagger documentation

Related Projects

Community-curated · Updated weekly · 100% open source

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Adding structured request/response validation to existing Flask applications

Projects needing support for both marshmallow schemas and Pydantic models

Teams wanting Flask compatibility with API-focused enhancements

Prototyping APIs quickly with interactive documentation

Migrating from Flask to a more API-centric framework without rewriting

Not Ideal For

High-performance, async-first applications requiring native concurrency support
Projects needing built-in ORM, admin interfaces, or full-stack framework features
Teams already heavily invested in FastAPI or Django REST Framework with no need for Flask compatibility
Simple prototyping where the overhead of schemas and decorators outweighs benefits

Pros & Cons

Pros

Automatic OpenAPI Documentation

Generates OpenAPI specs and interactive docs (Swagger UI, Redoc, etc.) out of the box, eliminating manual documentation work as shown in the README examples.

Flexible Schema Support

Works with both marshmallow schemas and Pydantic models via a pluggable adapter, giving developers choice without locking into one validation system.

Full Flask Compatibility

100% compatible with the Flask ecosystem, allowing seamless use of existing Flask extensions and patterns, as emphasized in the migration guide.

Declarative API Syntax

Uses decorators like @app.input() and @app.output() for clean request validation and response serialization, reducing boilerplate code in examples.

Cons

Performance Overhead

As a wrapper on Flask, it adds abstraction layers that can introduce slight latency compared to bare Flask or more optimized frameworks like FastAPI.

Limited Native Async Support

Async support requires an extra install ('apiflask[async]') and relies on Flask's async implementation, which isn't as robust as native async frameworks.

Dependency on Flask Evolution

Breaking changes or issues in Flask directly impact APIFlask, and it lacks independent feature development for advanced API needs like built-in dependency injection.

Open Source Alternative To

APIFlask is an open-source alternative to the following products:

FastAPI

A modern, fast web framework for building APIs with Python 3.7+ based on standard Python type hints, with automatic OpenAPI documentation.

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