| RESTful API is an interface that two computer systems use to exchange information securely over the internet. Most business applications have to communicate with other internal and third-party applications to perform various tasks. | gRPC is a modern open source high performance Remote Procedure Call (RPC) framework that can run in any environment. It can efficiently connect services in and across data centers with pluggable support for load balancing, tracing, health checking and authentication. |
| REST API is a set of guidelines for designing web APIs without enforcing anything. | gRPC enforces rules by defining a .proto file that must be adhered to by both client and server for data exchange. |
| REST API provides a request-response communication model built on the HTTP 1.1 protocol. Therefore, when multiple requests reach the server, it is bound to handle each of them, one at a time. | gRPC follows a client-response model of communication for designing web APIs that rely on HTTP/2. Hence, gRPC allows streaming communication and serves multiple requests simultaneously. In addition to that, gRPC also supports unary communication similar to REST. |
| REST API typically uses JSON and XML formats for data transfer. | gRPC relies on Protobuf for an exchange of data over the HTTP/2 protocol. |
| In REST API, in most cases, uses JSON or XML that requires serialization and conversion into the target programming language for both client and server, thereby increasing response time and the possibility of errors while parsing the request/response. | gRPC provides strongly typed messages automatically converted using the Protobuf exchange format to the chosen programming language. |
| REST API is utilizing HTTP 1.1 requires a TCP handshake for each request. Hence, REST APIs with HTTP 1.1 can suffer from latency issues. | gRPC relies on HTTP/2 protocol, which uses multiplexed streams. Therefore, several clients can send multiple requests simultaneously without establishing a new TCP connection for each one. Also, the server can send push notifications to clients via the established connection. |
| REST APIs on HTTP 1.1 have universal browser support. | gRPC has limited browser support because numerous browsers (usually the older versions) have no mature support for HTTP/2. So, it may require gRPC-web and a proxy layer to perform conversions between HTTP 1.1 and HTTP/2. Therefore, at the moment, gRPC is primarily used for internal services. |
| REST API provides no built-in code generation features. However, we can use third-party tools like Swagger or Postman to produce code for API requests. | gRPC is using its protocol buffer compiler, which comes with native code generation features, compatible with several programming languages. |