The Clear-Site-Data HTTP header provides a way for the server to instruct the client (typically a web browser) to delete various types of data that the site may have stored on the client’s device. This functionality is important for maintaining users’ privacy and security, especially when they’re using public or shared devices.
Core Concept
The Clear-Site-Data HTTP response header is used to clear browsing data (cookies, storage, cache) associated with the requesting website. It supports a variety of directives that specify what type of data should be deleted.
Here is an example of a Clear-Site-Data header in an HTTP response:
Clear-Site-Data: "cookies", "storage"In this case, the server is instructing the client to delete cookies and all site data (except for cache) stored by the site issuing the request.
Understanding Directives
The Clear-Site-Data header uses a set of directives to specify what types of data should be deleted. The following are the directives supported by this header:
"cookies": Clears all cookies associated with the origin of the response URL. It doesn’t affect cookies from other origins."storage": Clears all local storage, IndexedDB databases, and service workers. It doesn’t clear the HTTP cache."cache": Clears the HTTP cache for the origin of the response URL. This directive has a significant performance impact; use it cautiously."executionContexts": Unloads all browsing contexts (windows, workers, etc.) of the origin in question."*": Clears all types of data. Use this directive with caution, as it has a significant impact on performance and user experience.
Practical Examples
Clearing Cookies and Storage
If you want to instruct the client to delete all cookies and storage data associated with your site, you would use the Clear-Site-Data header like this in the HTTP response:
Clear-Site-Data: "cookies", "storage"Clearing All Data
If you want to clear all types of data, you would use the "*" directive. This is what the HTTP response would look like:
Clear-Site-Data: "*"Remember that this directive should be used judiciously as it can significantly impact the performance and user experience.
Summary
The Clear-Site-Data HTTP response header provides a robust tool for maintaining user privacy and security by allowing the server to instruct the client to delete various types of data. Understanding its directives and their implications is crucial for developers and administrators who are responsible for managing user data. Despite the performance implications, when applied appropriately, this header can greatly improve user trust in a website, making it an indispensable part of any web security toolkit.
