A web developer requires a method for client-server data exchange that supports standard HTTP methods. What should they implement?

Implementing REST (Representational State Transfer) is the correct approach for a web developer looking for a method of client-server data exchange that supports standard HTTP methods. REST is an architectural style that leverages HTTP protocols for the communication between clients and servers, which means it can utilize standard methods like GET, POST, PUT, DELETE, and more. This is particularly advantageous in creating web services that are stateless, scalable, and can interact with resources using URLs.

Moreover, REST API provides a uniform interface, allowing different systems to communicate efficiently. It is widely adopted due to its simplicity and the conventional nature of HTTP methods, making it a standard choice for web development.

In contrast, Mongo refers to a database that is document-oriented and does not directly address the data exchange method between clients and servers. A browser extension is a tool that adds functionality to web browsers but does not inherently define a communication protocol. HTML5 is a markup language used for structuring content on the web; while it allows for some data handling capabilities, it is not specifically designed for client-server communication with the robust features provided by REST. Thus, using REST is the most appropriate choice for enabling effective data exchange within a web application.