REST vs gRPC in FastAPI: The Restaurant Analogy Every Developer Needs
If you’re building APIs with FastAPI, you’ve probably seen both REST and gRPC mentioned. But what do they actually mean in practice—and why would a single project use both?
Let’s make it simple using something we all understand: a restaurant.
🍽️ The Restaurant Analogy: REST and gRPC Explained
Imagine you run a restaurant. Customers can place orders in two ways:
1. Walk-In Customers (REST API)
- People walk in, sit down, look at the menu, and place an order.
- This is like using a browser, Postman, or a mobile app to interact with your FastAPI endpoints.
- It’s human-friendly, visible, and flexible.
Example endpoint:
GET /api/v1/menus
This lets anyone (with access) see your menu.
2. Phone Orders (gRPC API)
- Instead of walking in, another business calls your kitchen directly to place a fast order.
- This is how one backend talks to another—direct, structured, and fast.
Example interaction:
Call: MenuService.ListMenus()
Returns: List of menu items
This uses gRPC under the hood, which is great for performance and structured data exchange.
🏗️ Why You Might Use Both in FastAPI
In the same FastAPI project, you can support both REST and gRPC:
- Mobile or frontend users → use REST.
- Internal systems, microservices, or partners → use gRPC.
It’s like having both walk-in and phone ordering at your restaurant.
🗂️ Project File Examples
You might organize your project like this:
-
main.py– Starts your REST API (walk-ins). -
grpc_server.py– Starts a gRPC server in the same project (for phone orders). -
scripts/grpc_only.py– If you want to run just the gRPC server separately.
🚦 When to Use Each
| Client Type | Use This | Run This File |
|---|---|---|
| Humans, Browsers, Apps | REST API | main.py |
| Other Backends/Services | gRPC API |
grpc_server.py or scripts/grpc_only.py
|
🧑🍳 Real-World Example
Let’s say you’re building a food delivery platform:
- Customers use the mobile app (REST) to view menus and place orders.
- Partner restaurants use your gRPC API to sync their menus and send order status updates.
Both sets of users interact with your backend, but through different channels optimized for their needs.
🧠 Key Takeaways
- REST is great for human-facing clients.
- gRPC is optimized for backend-to-backend communication.
- FastAPI can support both, and it’s powerful to give each client the best experience.
- Think of REST as walk-in ordering, and gRPC as a private, high-speed phone line to the kitchen.
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