What is gRPC and how is it different from REST in system communication?
In modern system architecture, a common question arises: what is gRPC and how is it different from REST in system communication? Both gRPC and REST are popular methods for how different parts of a system talk to each other. Understanding their differences is important for building efficient systems, preparing for technical interviews, and designing robust software. This introduction explores why these two technologies matter and sets the stage for a detailed comparison. GraphQL is another modern approach to APIs (we cover it in our REST vs GraphQL vs gRPC article), but here we’ll focus on comparing gRPC and REST.
What is REST?
REST (Representational State Transfer) is an architectural style for designing networked applications. RESTful services typically use standard HTTP methods (GET, POST, PUT, DELETE) to manipulate resources identified by URLs. Key principles of REST include stateless communication (each request stands on its own) and a uniform interface for interactions. Responses are often formatted in human-readable JSON. These design principles ensure scalable and consistent systems – you can learn more from our resources on the 5 basic principles of REST API and on REST API design.
What is gRPC?
gRPC is an open-source framework developed by Google for high-performance Remote Procedure Calls (RPC). This RPC approach differs from REST’s resource-oriented design (see our REST vs RPC guide for more details). Unlike REST, which uses JSON over HTTP, gRPC uses HTTP/2 and Protocol Buffers (a compact binary format) for communication. Developers define a service (methods and data structures) in a .proto file, and gRPC generates client and server code from it. This means gRPC APIs are strongly typed and efficient in serialization. gRPC also supports bi-directional streaming, allowing clients and servers to send data continuously in real time. Thanks to its speed and efficiency, gRPC is commonly used for internal microservice communication and performance-critical systems (though you might need gRPC-web or proxies to call gRPC from a browser).
gRPC vs REST: Key Differences
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Performance and Efficiency: gRPC’s binary protocol (Protobuf over HTTP/2) allows it to handle many calls concurrently on a single connection. This leads to lower latency and less overhead compared to REST’s text-based JSON over HTTP. In practice, gRPC often outperforms REST, especially for high-volume or real-time communication.
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Streaming Support: REST follows a one-request-one-response pattern, whereas gRPC can stream data. A server or client can send a continuous flow of messages over a single connection (even bi-directionally). This capability makes gRPC ideal for scenarios like live updates or real-time chat that are hard to implement with pure REST.
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Ease of Use and Compatibility: REST is simple for developers to test and debug with minimal tools (even a web browser can call a REST endpoint and display JSON). gRPC requires generated client code and special tools to inspect messages. Therefore, REST is usually chosen for public APIs accessible by various clients, while gRPC shines for internal services where you control the environment and can leverage its performance.
When to Use REST vs When to Use gRPC
Choosing between gRPC and REST depends on your project’s requirements. Here are some guidelines:
When to Use REST
- Public or External APIs: Choose REST when exposing an API to a broad or unknown audience (for example, a public web service or third-party integration). REST uses standard HTTP and JSON, making it accessible to developers and easy for web browsers and other clients.
When to Use gRPC
- Internal Microservice Calls: Use gRPC for service-to-service calls when low latency or efficiency is critical. Its compact messages and HTTP/2 support handle high call volumes much better than REST. gRPC is ideal when you control both client and server and want a strict API contract.
- Real-Time Streaming: For applications like chat, live notifications, or video streaming, gRPC’s native streaming support makes continuous data exchange much easier and more efficient than trying to do the same with REST.
FAQs
Q1. Is gRPC faster than REST?
Yes. gRPC usually transmits data faster than REST because it uses a compact binary format over HTTP/2, which means lower latency than REST’s text-based JSON over HTTP.
Q2. Can I use both REST and gRPC in the same system?
Absolutely. You can use REST and gRPC together in one system. For example, expose a REST API for external clients (easy integration) while internal microservices communicate via gRPC for efficiency.
Q3. When should I choose gRPC over REST?
Use gRPC when you need high performance, streaming support, or strict type-safety in internal communications (like between microservices). If you need a simple, broadly accessible API for public use or quick development, REST is usually the better choice.
Conclusion
In summary, REST offers simplicity and broad compatibility, while gRPC provides high performance and streaming capabilities. Many systems use REST for public APIs and gRPC internally for efficiency. Understanding these trade-offs will help you make better architecture decisions and impress in system design interviews.
One technical interview tip: practice explaining whether you’d use gRPC or REST in a given scenario – it’s a question you might face in system design mock interview practice sessions.
If you want to deepen your system design skills, consider our courses Grokking the System Design Fundamentals and Grokking the System Design Interview. These courses provide in-depth lessons and hands-on practice to help you design scalable systems and ace your interviews.
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