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gRPC vs REST is a comparison between two API architectural styles that differ in how they handle communication, performance, and data exchange. REST uses HTTP and human-readable formats like JSON, making it simple and widely compatible, while gRPC uses HTTP/2 and Protocol Buffers, enabling faster, more efficient communication, especially in distributed systems.
Choosing between gRPC and REST depends on your use case, system architecture, and performance requirements. In this guide, you will learn the key differences, when to use each approach, and how to decide which is best for your application.
In short:
- Use REST for public APIs, browser-based applications, and systems that prioritise simplicity and compatibility.
- Use gRPC for internal services, microservices architectures, and high-performance, low-latency communication.
- REST relies on HTTP and JSON, making it easier to debug, integrate, and adopt.
- gRPC uses HTTP/2 and Protocol Buffers, resulting in smaller payloads and faster data exchange.
- gRPC supports streaming and bi-directional communication, while REST follows a request-response model.
- Many modern architectures combine both, using REST externally and gRPC internally.
Understanding what an API is
APIs stand for Application Programming Interfaces. These interfaces serve as a software intermediary that establishes specific determinations and rules for applications to interact and talk to each other. An API is responsible for delivering a response from a user to a system, which in turn is sent back from the system to the user. Does it still sound a bit confusing?
Let's imagine we are booking a hotel. We go to the hotel booking page on our laptop, and that page - which is connected to the Internet - sends data (our request) to a server. In turn, the server retrieves the data, interprets it, and then, once the required actions are executed, it sends a response back to us with the information on our interface. This process happens thanks to APIs.
An API specifies the types of requests that one application (web page or mobile app) can make to another and further establishes: how to make those requests; which data formats to use; and the practices that users have to follow.
This article compares gRPC (Google Remote Procedure Call) and REST (Representational State Transfer) because they represent the two most popular architectural styles when creating APIs.
APIs and Microservices
On the one hand, in a monolithic application, all the project's functionalities are included in a single unit, more precisely, in a single codebase. On the other hand, a microservice architecture comprises several smaller services that communicate with each other using protocols like HTTP. The component services that are part of the microservices architecture communicate and interact with each other through APIs. In other words, APIs allow all the services that are integrated into a microservice application to connect and communicate.
The most used architectural style is the REST API. However, there are three main models when building an API: RPC (Remote Procedure Call), REST (Representational State Transfer), and GraphQL. In this article, we will focus on the first two.
What is RPC?
RPC uses a client-server model. The requesting server (in other words, the client) requests a message that is translated by the RPC and sent to another server. Once the server receives the request, it sends the response back to the client. While the server is processing this call, the client is blocked, and the internal message passing within servers is hidden.
Further, RPC allows the client to request a function in a particular format and receive the response in the exact same format. Nonetheless, the method of submitting a call with RPC API is found in the URL. RPC supports remote procedure calls both in local and distributed environments.
Like a REST API, RPC also establishes the rules of interaction and how a user can submit "calls" (requests) to invoke methods that communicate and interact with the service.
What is REST?
When using REST APIs, the response from the back-end data is passed to the clients (or users) through the JSON or XML messaging format. This architectural model tends to follow the HTTP protocol. However, it is not uncommon for RPC designs to also select a couple of ideas from HTTP while maintaining the RPC model. In fact, the majority of modern APIs are implemented by mapping the APIs to the same HTTP protocol, despite the model used (RPC or REST).
When the REST API is publicly available, each service that integrates the microservice application can be presented to the user/client as a resource which can be accessed through the following HTTP commands:GET, DELETE, POST, and PUT.
What is gRPC?
gRPC stands for Google Remote Procedure Call and is a variant based on the RPC architecture. This technology follows an RPC API's implementation that uses HTTP 2.0 protocol, but HTTP is not presented to the API developer nor to the server. Hence, there is no need to worry about how the RPC concepts are mapped to HTTP, which reduces complexity.
Overall, gRPC aims to make data transmissions between microservices faster. It is based on the approach of determining a service, establishing the methods and respective parameters to enable remote calling and return types.
Moreover, it expresses the RPC API model in an IDL (interface description language), which offers a more straightway to determine remote procedures. By default, the IDL uses Protocol Buffers (but other alternatives are also available) to describe the service interface as well as the payload messages' structure.
gRPC and REST: comparison
Now that we have an overview of gRPC vs REST, let's look at their main differences.
HTTP 1.1 vs HTTP 2
REST APIs follow a request-response model of communication that is typically built on HTTP 1.1. Unfortunately, this implies that if a microservice receives multiple requests from multiple clients, the model has to handle each request at a time, which consequently slows the entire system. However, REST APIs can also be built on HTTP 2, but the request-response model of communication remains the same, which forbids REST APIs to make the most out of the HTTP 2 advantages, such as streaming communication and bidirectional support.
gRPC does not face a similar obstacle. It is built on HTTP 2 and instead follows a client-response communication model. These conditions support bidirectional communication and streaming communication due to gRPC's ability to receive multiple requests from several clients and handle those requests simultaneously by constantly streaming information. Plus, gRPC can also handle "unary" interactions like the ones built on HTTP 1.1.
In sum, gRPC is able to handle unary interactions and different types of streaming:
- Unary: when the client sends a single request and receives a single response.
- Server-streaming: when the server responds with a stream of messages to a client's request. Once all the data is sent, the server additionally delivers a status message to complete the process.
- Client-streaming: when the client sends a stream of messages and in turn receives a single response message from the server.
- Bidirectional-streaming: the two streams (client and server) are independent, meaning that they both can transmit messages in any order. The client is the one who initiates and ends the bidirectional streaming.
Browser Support
This aspect is probably one of the main REST API advantages over gRPC. On the one hand, REST is fully supported by all browsers. On the other hand, gRPC is still quite limited when it comes to browser support. Unfortunately, it requires gRPC-web and a proxy layer to perform conversions between HTTP 1.1 and HTTP 2. Therefore, gRPC ends up being mainly used for internal/private systems (API programs within a particular organisation’s backend data and application functionality).
Payload Data Structure
As previously mentioned, gRPC uses Protocol Buffer by default to serialize payload data. This solution is lighter since it enables a highly compressed format and reduces the messages' size. Further, Protobuf (or Protocol Buffer) is binary; thus, it serializes and deserializes structured data in order to communicate and transmit it. In other words, the strongly typed messages can be automatically converted from Protobuf to the client and server's programming language.
In contrast, REST mainly relies on JSON or XML formats to send and receive data. In fact, even though it does not mandate any structure, JSON is the most popular format due to its flexibility and ability to send dynamic data without necessarily following a strict structure. Another significant benefit of using JSON is its human-readability level, which Protobuf cannot compete with yet.
Nonetheless, JSON is not as light-weight or fast when it comes to data transmission. The reason for that lies in the fact that when using REST, JSON (or other formats) must be serialised and turned into the programming language used on both the client and server sides. This adds an extra step to the process of transmitting data which can consequently damage performance and open a possibility for errors.
Code Generation Features
Unlike gRPC, REST API does not provide in-built code generation features, meaning that developers must use a third-party tool like Swagger or Postman to produce code for API requests.
In contrast, gRPC has native code generation features due to its protoc compiler, which is compatible with several programming languages. This is particularly beneficial for microservices systems that integrate various services developed in different languages and platforms. All in all, the built-in code generator also facilitates creating SDK (Software Development Kit).
Performance Benchmarks: gRPC vs REST
When evaluating gRPC vs REST performance, the differences are most evident in latency, payload size, and throughput—particularly in microservices and distributed systems.
Key Benchmark Insights
- Latency: gRPC typically achieves lower latency due to its use of HTTP/2 and binary serialisation (Protocol Buffers).
- Payload Size: Protobuf messages are significantly smaller than JSON, reducing bandwidth usage.
- Throughput: gRPC supports multiplexing and streaming, enabling higher request throughput under load.
Example Benchmark Findings
- According to Cloud Native Computing Foundation (CNCF), binary protocols like Protobuf can reduce payload size by up to 70–90% compared to JSON, depending on the data structure.
- Benchmarks from Google’s gRPC documentation show that gRPC can deliver lower response times and higher efficiency in high-concurrency environments due to HTTP/2 multiplexing.
- Research published highlights that HTTP/2-based communication (used by gRPC) improves performance in distributed systems by reducing connection overhead and enabling parallelism.
Key Takeaway
gRPC is generally more performant than REST in high-load, low-latency environments, while REST remains sufficient for standard web-based interactions.
Real-World Use Cases: When gRPC vs REST Is Used
Understanding how each architectural style is applied in real-world systems helps clarify when to choose one over the other.
When gRPC Is Used
1. Microservices Communication (Internal Systems)
gRPC is widely used for service-to-service communication in microservices architectures where performance and efficiency are critical.
- Example: Internal backend systems handling millions of requests per second
- Benefit: Reduced latency and efficient binary communication
2. Real-Time Streaming Applications
gRPC supports bidirectional streaming, making it suitable for:
- Live data feeds
- Chat systems
- Financial trading platforms
3. Mobile and IoT Systems
Due to smaller payload sizes, gRPC is ideal for:
- Mobile apps with limited bandwidth
- IoT devices requiring efficient data transmission
When REST Is Used
1. Public APIs (Web-Facing Services)
REST remains the standard for:
- Public-facing APIs
- Third-party integrations
- Reason: Broad compatibility with browsers and tools
2. CRUD-Based Applications
REST is ideal for applications that:
- Perform standard Create, Read, Update, Delete operations
- Do not require real-time streaming
3. Simpler Architectures
REST is often preferred when:
- Ease of implementation is prioritised
- Teams require flexibility and readability (JSON)
gRPC and REST: comparison table
| Feature | REST | gRPC | Best choice |
|---|---|---|---|
| Architecture style | Resource-based communication over HTTP | Remote procedure calls between services | Depends on system design |
| Data format | Usually JSON | Protocol Buffers by default | REST for readability, gRPC for efficiency |
| Transport | HTTP/1.1 commonly used | Built on HTTP/2 | gRPC for speed and multiplexing |
| Performance | Good for many standard web use cases | Typically faster with smaller payloads | gRPC |
| Streaming support | Limited, usually request-response | Supports client, server, and bidirectional streaming | gRPC |
| Browser support | Excellent and widely supported | Limited, often requires gRPC-Web | REST |
| Ease of debugging | Easy to inspect with standard tools | More complex due to binary payloads | REST |
| Learning curve | Lower | Higher | REST for simpler adoption |
| Best use cases | Public APIs, web apps, third-party integrations | Microservices, internal systems, real-time communication | REST externally, gRPC internally |
When to use gRPC or REST?
Choosing between gRPC and REST depends on your architecture, performance requirements, and how your APIs will be consumed. While both can solve similar problems, they are optimised for different contexts.
Use REST when:
- You are building public APIs that need to be easily consumed by external developers
- Your application relies on browser-based clients or standard HTTP tooling
- You need seamless third-party integrations
- Simplicity, readability, and compatibility are more important than raw performance
Use gRPC when:
- You are designing microservices architectures with frequent service-to-service communication
- Your system requires low latency and high throughput
- You need real-time streaming, including bidirectional communication
- Your APIs are used primarily in internal systems rather than exposed publicly
Use both when:
- You want the best of both approaches by using REST for external APIs and gRPC for internal communication between services
- You are scaling a platform where developer experience externally and performance internally are both critical
This hybrid approach is increasingly common in modern architectures, as it allows teams to balance flexibility, performance, and ease of integration without compromise.
Is gRPC better than REST API?
Is gRPC better than REST API? Both gRPC and REST API have their use cases. gRPC excels in high-performance environments, supports bidirectional streaming, and uses Protocol Buffers for efficient serialization. REST API is simpler, more flexible, and better suited for use with web applications or when interacting with multiple programming languages.
Frequently Asked Questions
What is REST?
REST, or Representational State Transfer, is a popular architectural style for building web services. It uses standard HTTP methods like GET, POST, DELETE, and PUT to communicate between clients and servers. REST is known for its simplicity and statelessness, making it highly suitable for web-based applications and microservices architectures. It typically uses JSON or XML for data exchange.
What is gRPC?
gRPC is an open-source framework developed by Google for efficient and high-performance communication between microservices. It stands out because it uses HTTP/2 for transport and Protocol Buffers (Protobuf) for its serialisation format. gRPC enables direct client-server communications and streaming capabilities, making it faster and more efficient for specific use cases.
What's the Difference Between gRPC vs REST?
The key differences between gRPC vs REST lie in their protocols, data formats, API designs, and streaming capabilities. gRPC uses HTTP/2 and Protobuf, offering advantages like smaller payloads and bidirectional streaming. Conversely, REST relies on the more traditional HTTP/1.1 and JSON/XML formats, focusing on stateless communication and resource manipulation through standard HTTP verbs.
Is gRPC better than REST?
Whether gRPC is better than REST depends on your project's specific requirements. gRPC offers benefits in performance, efficiency, and suitability for microservices and real-time data streaming. REST shines with its simplicity, wide adoption, and ease of use for web-based services. Each has its place, depending on your application's needs.
Is gRPC always faster than REST?
gRPC is generally faster than REST due to its use of HTTP/2 and Protobuf, which enable more efficient data serialisation and reduced latency. However, the performance advantage depends on the specific use case, including the nature of the data being transmitted and the network conditions.
Is gRPC still used?
Yes, gRPC is actively used and developed. It's particularly favoured in microservices architectures where performance and efficient communication are critical. Its support for multiple programming languages and platforms further contributes to its popularity in diverse tech ecosystems.
Why is gRPC so popular?
gRPC's popularity stems from its high performance, efficiency in communication, and versatility across languages and platforms. Its ability to handle streaming data and complex communication patterns between microservices makes it a strong candidate for modern, scalable applications.
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