After over a decade of building APIs with Express.js, I recently dove into FastAPI for a client project. What I found was a framework that elegantly solved problems I'd been working around for years. It's quickly becoming my go-to choice for standalone API development.
The Python Renaissance
Let's address the elephant in the room first. If you're a Node.js developer like me, you might have some preconceptions about Python. Maybe you remember the horror stories about Python 2 to 3 migration nightmares, or you remember when Python web frameworks felt clunky compared to Express.js.
Those days are behind us. Modern Python tooling has caught up and, in some ways, surpassed what we take for granted in the Node.js ecosystem. Package management with Poetry rivals npm's developer experience, and the async/await patterns we love in Node.js are now first-class citizens in Python.
But here's the game-changer for me: Python's type hints now provide the static type checking that drew me to TypeScript in the first place. As someone who went all-in on Express.js specifically because TypeScript brought strong typing to my JavaScript code, seeing Python evolve to offer similar compile-time safety feels like a similar moment. Modern Python with type hints gives you the best of both worlds—the readability Python is famous for, plus the confidence that comes from catching type errors before runtime.
A key enabler of this maturation is ASGI (Asynchronous Server Gateway Interface), which allows Python web applications to handle requests asynchronously, similar to how Node.js processes events. This means FastAPI can deliver performance that rivals Node.js while maintaining Python's developer-friendly syntax and now with the type safety I've come to depend on.
Familiar Patterns, Less Code
Coming from Express.js, FastAPI feels immediately familiar. Both frameworks embrace middleware-driven architectures and async/await patterns. Here's a POST endpoint for creating a blog post in Express with TypedJSON:
And here's the FastAPI equivalent:
The FastAPI version is dramatically cleaner, as it's doing some heavy lifting behind the scenes. The CreatePostDto type annotation automatically validates and deserializes the request body, while the PostOutputDto return type ensures proper serialization and generates OpenAPI documentation—all without any manual setup.
The Goldilocks Zone of Opinionation
This is where FastAPI really shines compared to Express.js. Over my years building Express APIs, I've developed what I call my "Express.js survival kit"—a collection of patterns and libraries that fill the framework's gaps:
Request validation with TypedJSON
Response serialization with manual JSON handling
API documentation with Swagger annotations
Dependency injection with tsyringe
Authentication middleware built from scratch
Express.js gives you the freedom to choose your own adventure, but that freedom comes with real costs. Every project accumulates custom code for basic functionality that needs to be maintained and debugged. Developers spend time managing dependency upgrades and resolving conflicts between various libraries. Worse, different projects end up with inconsistent versions of these foundational solutions, making it harder to move between codebases or maintain standards across your organization.
FastAPI hits the sweet spot. It's opinionated enough to include the essentials—validation, serialization, documentation, dependency injection—but flexible enough to let you structure your application how you want. You're not locked into a heavyweight framework like NestJS, but you're also not rebuilding the same foundational code for every project.
When to Choose FastAPI
I'm not abandoning Node.js—my full-stack React applications still benefit from the unified JavaScript ecosystem, especially with the recent maturity in server-side rendering frameworks like Next.js and Remix. These tools have largely eliminated the need for separate API layers in smaller projects by enabling tight integration between frontend and backend logic.
However, for projects where the solution architecture clearly requires a standalone API—microservices, mobile-first applications, or systems serving multiple client types—FastAPI offers compelling advantages over Express.js.
FastAPI makes sense when you want:
Integration with existing Python codebases or data pipelines
AI/ML-heavy applications where you'll be doing Jupyter notebook-driven debugging and prototyping
Clean separation between your API layer and any frontend rendering concerns
A modern framework without the overhead of enterprise solutions like Spring or NestJS
Fast development with built-in best practices for standalone API services
Automatic API documentation that stays current
Looking Forward
The best technologies solve problems you didn't know you had. FastAPI does that by eliminating the boilerplate and architectural decisions that have become second nature in Express.js development. It's not just about Python vs Node.js—it's about choosing tools that let you focus on building features instead of rebuilding the same foundational code.
As someone who's been committed to the JavaScript ecosystem for over a decade, exploring FastAPI has been a reminder that the best developers remain curious about better ways to solve problems. Sometimes the grass really is greener on the other side.
At Hypercolor Digital, we believe in using the right tool for the job. While we continue to build exceptional products with React and Node.js, we're always exploring technologies that can deliver better outcomes for our clients. Interested in learning more about our approach to technology selection? Get in touch.