Which data format is predominantly used in REST to support browser clients?

• A. XML
• B. YAML
• C. CSV
• D. JSON

Answer: (D)

JSON is the preferred data format for REST when the client is a web browser because its lightweight syntax maps directly to JavaScript objects, making it easy for browser code to parse and use data with minimal overhead. Browsers have native support for JSON via built-in parsing (like JSON.parse) and common APIs (such as fetch) that work smoothly with the application/json MIME type, enabling quick retrieval and immediate conversion into usable data structures. This tight integration speeds development and reduces payload complexity compared to alternatives. XML, while workable, is more verbose and requires more processing to extract data, which adds overhead for browser apps. YAML and CSV aren’t ideal for broad REST payloads in browsers since they lack native, straightforward browser parsing or the flexibility to represent complex nested data. For these reasons, JSON dominates REST responses intended for browser clients.