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gRPC vs REST: Which is Better for Your APIs?

API Testing

Shreya Srivastava

Nov 24, 2023

Introduction

In the world of API development, two major players are REST (Representational State Transfer) and gRPC (gRPC Remote Procedure Call). Choosing the right one for your project can significantly impact performance, scalability, and ease of development. This blog will delve into the differences, benefits, and use cases of REST and gRPC, helping you make an informed decision.

If you’re new to API testing, you might want to start with our beginner’s guide on What is API Testing and How to Get Started

What is an API?

An Application Programming Interface (API) is a set of rules that allows different software entities to communicate with each other. APIs enable the integration of new features and services into applications, ensuring seamless interaction between different systems.

Why APIs are Important

APIs are the backbone of modern software development. They allow developers to use existing services and frameworks, promote modularity, and facilitate rapid development. Whether it's a web application, mobile app, or cloud service, APIs play a crucial role.

What is an API?

Why APIs are Important

What is an API?

Why APIs are Important

Introduction to REST

What is REST?

REST, or Representational State Transfer, is an architectural style for designing networked applications. RESTful services use HTTP requests to perform CRUD (Create, Read, Update, Delete) operations.
"In simpler terms, a REST API is a set of rules that helps apps share information easily."

An API, or Application Programming Interface, is a set of rules and protocols that enable different software components to interact and exchange data. APIs are essential components of all modern applications, quietly powering how our favorite apps, services, and devices communicate behind the scenes. Without APIs, our daily digital experiences would look very different.

There are various architectural styles for building APIs, each with its own benefits and trade-offs. REST is among the most popular, prized for its simplicity, statelessness, and resource-based communication model. This makes REST a flexible choice for web services that need to scale and evolve over time.

Key Principles of REST

Statelessness: Each request from a client to a server must contain all the information needed to understand and process the request.
Client-Server Architecture: The client and server are separate entities, promoting scalability and flexibility.
Cacheability: Responses should be defined as cacheable or non-cacheable to improve performance.
Layered System: A client cannot tell if it is connected directly to the end server or an intermediary.
Uniform Interface: Simplifies and decouples the architecture, enabling each part to evolve independently.

RESTful Web Services

RESTful web services typically use HTTP methods such as GET, POST, PUT, and DELETE. They leverage URLs to identify resources and often use JSON or XML for data interchange.

Design Pattern: Resource-Oriented

REST APIs follow a resource-oriented design pattern. This means clients interact with resources—such as users, products, or orders—through dedicated API endpoints. Each resource is accessed or modified using a standard set of HTTP methods, making the interface predictable and easy to understand.

What is REST?

Key Principles of REST

Statelessness: Each request from a client to a server must contain all the information needed to understand and process the request.
Client-Server Architecture: The client and server are separate entities, promoting scalability and flexibility.
Cacheability: Responses should be defined as cacheable or non-cacheable to improve performance.
Layered System: A client cannot tell if it is connected directly to the end server or an intermediary.
Uniform Interface: Simplifies and decouples the architecture, enabling each part to evolve independently.

RESTful Web Services

RESTful web services typically use HTTP methods such as GET, POST, PUT, and DELETE. They leverage URLs to identify resources and often use JSON or XML for data interchange.

Design Pattern: Resource-Oriented

What is REST?

Key Principles of REST

Statelessness: Each request from a client to a server must contain all the information needed to understand and process the request.
Client-Server Architecture: The client and server are separate entities, promoting scalability and flexibility.
Cacheability: Responses should be defined as cacheable or non-cacheable to improve performance.
Layered System: A client cannot tell if it is connected directly to the end server or an intermediary.
Uniform Interface: Simplifies and decouples the architecture, enabling each part to evolve independently.

RESTful Web Services

RESTful web services typically use HTTP methods such as GET, POST, PUT, and DELETE. They leverage URLs to identify resources and often use JSON or XML for data interchange.

Design Pattern: Resource-Oriented

Introduction to gRPC

What is gRPC?

gRPC is a high-performance, open-source framework developed by Google. It uses HTTP/2 for transport, Protocol Buffers (protobufs) for serialization, and it supports multiple programming languages.
"In simple terms, gRPC is like a speedy messenger that helps different programs understand each other, making it easier for them to work together, even if they're far away."
But what exactly makes gRPC such a powerful tool for connecting distributed systems? At its core, gRPC is an implementation of the Remote Procedure Call (RPC) protocol, which means it enables a program running on one machine to seamlessly call functions on another machine, as if both were running side by side.

Key Principles of gRPC

Efficient Communication: gRPC uses HTTP/2, which allows for multiplexing multiple requests over a single connection, reducing latency and supporting features like flow control and header compression.
Strongly Typed Contracts: gRPC uses Protocol Buffers, which provide a clear and efficient way to define service methods and message structures. These strongly typed service contracts ensure that both client and server share the same expectations for data and communication.
Bi-Directional Streaming: Supports bi-directional streaming, enabling real-time communication. With HTTP/2 under the hood, gRPC allows both client and server to send and receive data streams simultaneously, making it ideal for interactive applications.
Language Agnostic: Provides tools to generate client and server code in multiple languages, so teams can work in their preferred programming environments without friction.

Both REST and gRPC are powerful tools in the API landscape, each suited to particular needs and scenarios. Understanding their core principles and how they enable software components to communicate is the first step in choosing the right tool for your next project.

gRPC Services

gRPC services define methods using Protocol Buffers. Each service consists of a set of RPC (Remote Procedure Call) methods that can be called remotely by clients. The use of Protocol Buffers not only boosts serialization efficiency but also enables automatic code generation across diverse languages, like Java, Python, Go, and more. This makes building robust, consistent APIs across a distributed system much more straightforward.

With all these features, gRPC streamlines the way modern applications—whether they're microservices or massive cloud deployments—communicate with each other, setting the stage for high performance and easy scalability.

Design Pattern: Service-Oriented

Unlike REST's focus on resources, gRPC APIs follow a service-oriented design. Here, the server defines callable functions—known as methods—that the client can invoke directly, much like calling a function in your own code. This approach streamlines communication and makes defining complex operations straightforward, especially for distributed systems.

Design Patterns: Service-Oriented vs. Resource-Oriented

Let’s talk about how REST and gRPC organize their APIs—because they take two very different approaches.

gRPC takes a service-oriented approach.
Imagine treating your API like a set of well-defined functions living on the server. With gRPC, you specify which functions are available, and clients can call these as if they were simply invoking local methods, even though everything is happening over the network. This creates a contract-based environment where each operation is clearly defined using Protocol Buffers, making it easy for multiple programming languages to play together harmoniously. It’s all about focusing on actions (“Do this thing for me!”), rather than fiddling with discrete resources.
REST is resource-oriented by design.
Here, the focus shifts from actions to resources. REST organizes information as addressable entities—think of “documents,” “users,” or “orders”—which you interact with using standard HTTP methods like GET, POST, PUT, and DELETE. Each API endpoint corresponds to a specific resource, so clients request or mutate data by working with these resources, rather than asking the server to perform named functions directly.

In summary, gRPC’s service-oriented style is all about calling remote procedures, while REST’s resource-oriented design lets you work with digital “things” from afar. This fundamental difference impacts how you design, build, and interact with modern APIs.

What is gRPC?

Key Principles of gRPC

Efficient Communication: gRPC uses HTTP/2, which allows for multiplexing multiple requests over a single connection, reducing latency and supporting features like flow control and header compression.
Strongly Typed Contracts: gRPC uses Protocol Buffers, which provide a clear and efficient way to define service methods and message structures. These strongly typed service contracts ensure that both client and server share the same expectations for data and communication.
Bi-Directional Streaming: Supports bi-directional streaming, enabling real-time communication. With HTTP/2 under the hood, gRPC allows both client and server to send and receive data streams simultaneously, making it ideal for interactive applications.
Language Agnostic: Provides tools to generate client and server code in multiple languages, so teams can work in their preferred programming environments without friction.

gRPC Services

Design Pattern: Service-Oriented

Design Patterns: Service-Oriented vs. Resource-Oriented

Let’s talk about how REST and gRPC organize their APIs—because they take two very different approaches.

gRPC takes a service-oriented approach.
Imagine treating your API like a set of well-defined functions living on the server. With gRPC, you specify which functions are available, and clients can call these as if they were simply invoking local methods, even though everything is happening over the network. This creates a contract-based environment where each operation is clearly defined using Protocol Buffers, making it easy for multiple programming languages to play together harmoniously. It’s all about focusing on actions (“Do this thing for me!”), rather than fiddling with discrete resources.
REST is resource-oriented by design.
Here, the focus shifts from actions to resources. REST organizes information as addressable entities—think of “documents,” “users,” or “orders”—which you interact with using standard HTTP methods like GET, POST, PUT, and DELETE. Each API endpoint corresponds to a specific resource, so clients request or mutate data by working with these resources, rather than asking the server to perform named functions directly.

What is gRPC?

Key Principles of gRPC

Efficient Communication: gRPC uses HTTP/2, which allows for multiplexing multiple requests over a single connection, reducing latency and supporting features like flow control and header compression.
Strongly Typed Contracts: gRPC uses Protocol Buffers, which provide a clear and efficient way to define service methods and message structures. These strongly typed service contracts ensure that both client and server share the same expectations for data and communication.
Bi-Directional Streaming: Supports bi-directional streaming, enabling real-time communication. With HTTP/2 under the hood, gRPC allows both client and server to send and receive data streams simultaneously, making it ideal for interactive applications.
Language Agnostic: Provides tools to generate client and server code in multiple languages, so teams can work in their preferred programming environments without friction.

gRPC Services

Design Pattern: Service-Oriented

Design Patterns: Service-Oriented vs. Resource-Oriented

Let’s talk about how REST and gRPC organize their APIs—because they take two very different approaches.

gRPC takes a service-oriented approach.
Imagine treating your API like a set of well-defined functions living on the server. With gRPC, you specify which functions are available, and clients can call these as if they were simply invoking local methods, even though everything is happening over the network. This creates a contract-based environment where each operation is clearly defined using Protocol Buffers, making it easy for multiple programming languages to play together harmoniously. It’s all about focusing on actions (“Do this thing for me!”), rather than fiddling with discrete resources.
REST is resource-oriented by design.
Here, the focus shifts from actions to resources. REST organizes information as addressable entities—think of “documents,” “users,” or “orders”—which you interact with using standard HTTP methods like GET, POST, PUT, and DELETE. Each API endpoint corresponds to a specific resource, so clients request or mutate data by working with these resources, rather than asking the server to perform named functions directly.

REST vs gRPC: A Comparative Analysis

Before diving into the differences, it's important to note that REST and gRPC share several foundational similarities that make them popular choices for building modern APIs:

Client-Server Architecture: Both frameworks follow a clear client-server model, where clients send requests and servers respond with data or actions.
HTTP as the Underlying Protocol: REST typically uses HTTP/1.1, while gRPC leverages HTTP/2, but both utilize HTTP for communication.
Language Agnostic: REST and gRPC are both language-agnostic, allowing clients and servers to be implemented in a wide range of programming languages.
Statelessness: Both are designed to be stateless—each request contains all the information needed for the server to process it, eliminating the need for the server to store session state.

Similarities and Differences: gRPC vs REST

Before diving into what sets gRPC and REST apart, it helps to recognize where they align:

Client/Server Architecture: Both gRPC and REST operate on a client-server model. Clients make requests and servers respond, keeping the roles well-defined and separate.
Use of HTTP: Each leverages HTTP as its transport foundation—REST typically runs over HTTP/1.1, while gRPC takes advantage of HTTP/2 for more advanced features.
Language Agnosticism: Whether you’re coding in Python, Java, Go, or something else, both gRPC and REST offer broad language support, making them suitable for diverse tech stacks.
Statelessness: Both frameworks are stateless. Every request carries all the information the server needs, so there’s no need for the server to remember previous interactions.

Key Differences

Performance:
gRPC generally offers better performance than REST due to its use of HTTP/2, binary serialization, and efficient communication mechanisms. REST, while still performant, can be slower due to its reliance on text-based protocols and HTTP/1.1.
Scalability:
Both REST and gRPC can scale effectively, but gRPC's efficient communication and support for bi-directional streaming can make it more suitable for high-throughput, low-latency applications.
Ease of Development:
REST is easier to implement and understand, making it a popular choice for many developers. gRPC, while more complex, offers tools and libraries that simplify development, particularly for large-scale applications.
Security:
Both REST and gRPC support common security mechanisms such as TLS. REST, with its maturity, has a wide range of security practices and tools. gRPC, being newer, also provides robust security but might require additional considerations for complex security requirements.
Interoperability:
REST, with its use of HTTP and standard data formats like JSON and XML, is highly interoperable. gRPC, while language-agnostic, relies on Protocol Buffers, which may require additional tooling for integration with systems that do not natively support protobufs.
Payload Size:
gRPC messages are typically smaller due to binary serialization with Protocol Buffers, which can lead to reduced bandwidth usage and faster transmission. REST messages, using JSON or XML, can be larger and less efficient.
Error Handling:
REST uses standard HTTP status codes for error handling, which are widely understood. gRPC has its own status codes and provides detailed error messages, offering more granular error handling.

By understanding these core similarities and differences, you can make an informed decision about which protocol best fits your project's needs.

When it comes to data validation, REST and gRPC take distinct paths.

With gRPC, the use of Protocol Buffers (protobufs) means data structure and rules are defined up front. This creates a clear, strongly-typed contract between client and server. Every message exchanged must conform to these predefined structures—invalid data simply won’t make it through, as validation happens automatically during serialization and deserialization.

On the other hand, REST typically works with JSON, a text-based and loosely typed format. This flexibility comes at a cost: the server must manually check incoming data for correct types, presence of required fields, and proper formatting. As a result, REST APIs require additional lines of code and processing time to validate each request, while gRPC’s validation is essentially “baked in” at the protocol level.

Data Validation Differences Between gRPC and REST

One of the important distinctions between gRPC and REST lies in how each handles data validation.

With gRPC, data validation is essentially built into the framework. When defining the API using Protocol Buffers, you explicitly specify each message’s structure, including required fields and data types. This contract acts as a source of truth for both the client and server. As a result, any message exchanged must conform to the defined schema, and validation is handled automatically as part of the serialization and deserialization process. This guarantees that invalid or unexpected data is rejected early, streamlining communication and reducing manual checks.

REST, on the other hand, operates mainly with flexible data formats like JSON or XML. While this flexibility offers advantages, it also means that incoming data must be manually validated by the server. Developers need to write additional code to ensure that the data adheres to expected structures, types, and constraints. This manual validation step can add complexity and modestly impact performance, as each API endpoint must implement its own checking mechanisms.

In summary, gRPC’s contract-driven approach automates much of the validation process, while REST requires explicit runtime validation to maintain data integrity.

Before diving into the differences, it's important to note that REST and gRPC share several foundational similarities that make them popular choices for building modern APIs:

Client-Server Architecture: Both frameworks follow a clear client-server model, where clients send requests and servers respond with data or actions.
HTTP as the Underlying Protocol: REST typically uses HTTP/1.1, while gRPC leverages HTTP/2, but both utilize HTTP for communication.
Language Agnostic: REST and gRPC are both language-agnostic, allowing clients and servers to be implemented in a wide range of programming languages.
Statelessness: Both are designed to be stateless—each request contains all the information needed for the server to process it, eliminating the need for the server to store session state.

Similarities and Differences: gRPC vs REST

Before diving into what sets gRPC and REST apart, it helps to recognize where they align:

Client/Server Architecture: Both gRPC and REST operate on a client-server model. Clients make requests and servers respond, keeping the roles well-defined and separate.
Use of HTTP: Each leverages HTTP as its transport foundation—REST typically runs over HTTP/1.1, while gRPC takes advantage of HTTP/2 for more advanced features.
Language Agnosticism: Whether you’re coding in Python, Java, Go, or something else, both gRPC and REST offer broad language support, making them suitable for diverse tech stacks.
Statelessness: Both frameworks are stateless. Every request carries all the information the server needs, so there’s no need for the server to remember previous interactions.

Key Differences

Performance:
gRPC generally offers better performance than REST due to its use of HTTP/2, binary serialization, and efficient communication mechanisms. REST, while still performant, can be slower due to its reliance on text-based protocols and HTTP/1.1.
Scalability:
Both REST and gRPC can scale effectively, but gRPC's efficient communication and support for bi-directional streaming can make it more suitable for high-throughput, low-latency applications.
Ease of Development:
REST is easier to implement and understand, making it a popular choice for many developers. gRPC, while more complex, offers tools and libraries that simplify development, particularly for large-scale applications.
Security:
Both REST and gRPC support common security mechanisms such as TLS. REST, with its maturity, has a wide range of security practices and tools. gRPC, being newer, also provides robust security but might require additional considerations for complex security requirements.
Interoperability:
REST, with its use of HTTP and standard data formats like JSON and XML, is highly interoperable. gRPC, while language-agnostic, relies on Protocol Buffers, which may require additional tooling for integration with systems that do not natively support protobufs.
Payload Size:
gRPC messages are typically smaller due to binary serialization with Protocol Buffers, which can lead to reduced bandwidth usage and faster transmission. REST messages, using JSON or XML, can be larger and less efficient.
Error Handling:
REST uses standard HTTP status codes for error handling, which are widely understood. gRPC has its own status codes and provides detailed error messages, offering more granular error handling.

By understanding these core similarities and differences, you can make an informed decision about which protocol best fits your project's needs.

When it comes to data validation, REST and gRPC take distinct paths.

Data Validation Differences Between gRPC and REST

One of the important distinctions between gRPC and REST lies in how each handles data validation.

In summary, gRPC’s contract-driven approach automates much of the validation process, while REST requires explicit runtime validation to maintain data integrity.

Before diving into the differences, it's important to note that REST and gRPC share several foundational similarities that make them popular choices for building modern APIs:

Client-Server Architecture: Both frameworks follow a clear client-server model, where clients send requests and servers respond with data or actions.
HTTP as the Underlying Protocol: REST typically uses HTTP/1.1, while gRPC leverages HTTP/2, but both utilize HTTP for communication.
Language Agnostic: REST and gRPC are both language-agnostic, allowing clients and servers to be implemented in a wide range of programming languages.
Statelessness: Both are designed to be stateless—each request contains all the information needed for the server to process it, eliminating the need for the server to store session state.

Similarities and Differences: gRPC vs REST

Before diving into what sets gRPC and REST apart, it helps to recognize where they align:

Client/Server Architecture: Both gRPC and REST operate on a client-server model. Clients make requests and servers respond, keeping the roles well-defined and separate.
Use of HTTP: Each leverages HTTP as its transport foundation—REST typically runs over HTTP/1.1, while gRPC takes advantage of HTTP/2 for more advanced features.
Language Agnosticism: Whether you’re coding in Python, Java, Go, or something else, both gRPC and REST offer broad language support, making them suitable for diverse tech stacks.
Statelessness: Both frameworks are stateless. Every request carries all the information the server needs, so there’s no need for the server to remember previous interactions.

Key Differences

Performance:
gRPC generally offers better performance than REST due to its use of HTTP/2, binary serialization, and efficient communication mechanisms. REST, while still performant, can be slower due to its reliance on text-based protocols and HTTP/1.1.
Scalability:
Both REST and gRPC can scale effectively, but gRPC's efficient communication and support for bi-directional streaming can make it more suitable for high-throughput, low-latency applications.
Ease of Development:
REST is easier to implement and understand, making it a popular choice for many developers. gRPC, while more complex, offers tools and libraries that simplify development, particularly for large-scale applications.
Security:
Both REST and gRPC support common security mechanisms such as TLS. REST, with its maturity, has a wide range of security practices and tools. gRPC, being newer, also provides robust security but might require additional considerations for complex security requirements.
Interoperability:
REST, with its use of HTTP and standard data formats like JSON and XML, is highly interoperable. gRPC, while language-agnostic, relies on Protocol Buffers, which may require additional tooling for integration with systems that do not natively support protobufs.
Payload Size:
gRPC messages are typically smaller due to binary serialization with Protocol Buffers, which can lead to reduced bandwidth usage and faster transmission. REST messages, using JSON or XML, can be larger and less efficient.
Error Handling:
REST uses standard HTTP status codes for error handling, which are widely understood. gRPC has its own status codes and provides detailed error messages, offering more granular error handling.

By understanding these core similarities and differences, you can make an informed decision about which protocol best fits your project's needs.

When it comes to data validation, REST and gRPC take distinct paths.

Data Validation Differences Between gRPC and REST

One of the important distinctions between gRPC and REST lies in how each handles data validation.

In summary, gRPC’s contract-driven approach automates much of the validation process, while REST requires explicit runtime validation to maintain data integrity.

When to use REST vs. gRPC?

REST and gRPCs features make them suited for different use cases.

Best for Public Web Services: REST

REST’s features are well-suited to public web service APIs. REST uses the HTTP 1.1 protocol which has universal browser support. gRPC, on the other hand, is less compatible since it uses HTTP 2.0. While gRPC’s payload is smaller, REST’s primary payload format, JSON, is more flexible and friendly to browsers. REST also allows you to use other message formats HTML, plain text, XML, and YAML which adds to its flexibility.

Best for Internal APIs, IoT, and mobile: gRPC

gRPC has features that make it suited for internal APIs, IoT, and mobile development. These applications benefit from gRPC’s bi-directional streaming, small payload sizes, and built-in code generation. gRPC’s small message size makes it more performant and scalable than REST for these applications.

gRPC’s low browser support makes it suited to internal APIs (non-public) and mobile development. Mobile applications usually do not require a browser, and gRPC’s small message size can preserve the processing speed of the mobile device.

IoT APIs need bi-directional streaming because many devices may send messages to an API server concurrently. gRPC can process and respond to multiple requests from multiple clients at the same time. REST, on the other hand, only supports unary communication. IoT APIs also require lightweight messaging because of constrained bandwidth. Finally, it is easier to use gRPC to connect Internet of Things (IoT) devices such as phones to backend APIs.

Best for microservices: The jury is out

REST and gRPC are both used for microservices. While REST is more widely used for microservices, gRPC’s features are particularly suited to this domain.

Microservice architectures can leverage gRPC’s built-in code generation to allow microservices written in different programming languages to communicate. gRPC’s payload size and bi-directional streaming also allow faster and more efficient communication between microservices.
With gRPC, developers define their services and message formats using Protocol Buffers ( files). These definitions are then compiled, generating client and server code across multiple languages such as Go, Java, Python, and C#. For the client, the generated code includes method stubs that handle the serialization, network communication, and response parsing automatically. On the server side, developers receive a base class that they can implement to define the service’s business logic.

This native code generation streamlines development and reduces boilerplate, making it easier to build and maintain consistent APIs across a polyglot microservices ecosystem. In contrast, while REST APIs can be built in any language, they don’t offer this level of built-in, language-agnostic code generation out of the box.

One of gRPC’s key advantages comes from its use of Protocol Buffers (Protobuf) for defining services and data structures. Developers create files describing the service methods and messages, and then use the Protobuf compiler to generate client and server code in multiple programming languages—such as Go, Java, Python, and C#. This generated code streamlines the process: for clients, it includes method stubs that handle data serialization, network calls, and response handling; for servers, it provides a base class to implement the service logic. This automatic code generation reduces boilerplate, enforces consistency, and accelerates development across polyglot environments.

Although REST APIs can also be built in almost any language, they don’t provide native, standardized support for code generation. Developers working with REST often rely on third-party tools like Swagger/OpenAPI for similar functionality, but these lack the deep integration and out-of-the-box support that gRPC and Protobuf provide.

By combining efficient serialization, built-in code generation, and high-performance streaming, gRPC stands out as a strong option for communication between microservices, especially in large-scale, multi-language systems.

REST and gRPCs features make them suited for different use cases.

Best for Public Web Services: REST

Best for Internal APIs, IoT, and mobile: gRPC

Best for microservices: The jury is out

REST and gRPC are both used for microservices. While REST is more widely used for microservices, gRPC’s features are particularly suited to this domain.

REST and gRPCs features make them suited for different use cases.

Best for Public Web Services: REST

Best for Internal APIs, IoT, and mobile: gRPC

Best for microservices: The jury is out

REST and gRPC are both used for microservices. While REST is more widely used for microservices, gRPC’s features are particularly suited to this domain.