If you’ve been building APIs for a while, you’ve probably faced the question: Should I use REST or gRPC? Each technology brings something different to the table and picking the right one can feel tricky. In this blog, we’ll break down the differences, so you’ll know exactly when and why to use each.
Before jumping in let’s get the basics right.
What is an API (Application Programming Interface)?
APIs define how clients and servers communicate. As an example, it is like a menu in a restaurant. You (the client) order what you need using a certain format, and the kitchen (the server) gives you the result.
Now, let’s explore the two popular ways to build APIs: REST, gRPC
REST (Representational State Transfer)
REST is the most common style for building web APIs that makes communication between a client and a server.
HOW REST Works?
REST APIs use the HTTP protocol (the same one browsers use). The client sends an HTTP request, and the server sends back an HTTP response usually in JSON format.
(Note: Although JSON is the standard, REST APIs can use other formats like XML, YAML)
Key REST Principles
- Stateless
Each request is independent. The server doesn’t remember previous ones.
(All needed info must be sent in each request.)
- Client–Server Separation
The frontend (client) and backend (server) are separate systems that communicate via API.
- Uniform Interface
Every API call follows the same structure, making it easy to understand and use.
- Resource-based URLs
Data is organized as resources, not actions.
Use when:
- You need simple, standard, and widely supported APIs.
- Your data is not too complex, and fixed endpoints are enough
- You want easy debugging and testing
Pros
- Easy to understand and use
- Uses standard HTTP, no special setup
- Human-readable (uses JSON and URLs)
- Great for public APIs
Cons
- Text-based (larger data size and slower than gRPC for heavy traffic)
- No built-in streaming (can’t send continuous data easily)
- Over-fetching (you get more data than needed)
- Under-fetching (you need to make multiple requests for related data)
gRPC (Google Remote Procedure Call)
gRPC is a high-performance open-source framework developed by Google that allows different systems or microservices to communicate fast and efficiently, even if they’re written in different programming languages.
It’s built on top of HTTP/2 and unlike REST, which uses text-based formats (usually JSON), gRPC uses Protocol Buffers (Protobufs) for communication, which is faster and more compact.
Instead of working with URLs, you call functions directly like calling methods in code.
Use when:
- You need fast communication between microservices.
- You care about performance and efficiency.
- Both sides (client and server) can understand Protocol Buffers (.proto files).
Pros
- Very fast and efficient
- Supports streaming (send multiple messages in one connection)
- Great for microservices and internal systems
Cons
- Not as beginner friendly as REST
- Limited browser support (needs special libraries)
- Harder to debug (binary data isn’t human-readable)