ReqBlock is a free Chrome add-on developed by Andrási István. It falls under the category of Browsers and specifically the subcategory of Add-ons & Tools.

ReqBlock is a simple request blocker that allows users to block requests with simple URL patterns. The add-on provides an options page where users can specify a blacklist of URLs to block. The configuration is a straightforward block of text, making it easy to export and import the blacklist by simply copying and pasting.

One of the standout features of ReqBlock is the ability to collect requests while the options page is open. This allows users to easily update the blacklist based on the requests being made.

ReqBlock matches a request URL to a line in the blacklist by filling in the spaces to create an exact substring match. If a request URL matches any line in the blacklist, it is blocked. The add-on ignores empty lines and lines starting with a #, providing a way to comment and group rules.

Additionally, ReqBlock offers a tidy button that removes leading and trailing whitespace from every line and sorts rules inside groups separated by comments and empty lines.

ReqBlock's configurations are backed up by sync storage if available. If sync storage is not available, the add-on falls back to local storage. While ReqBlock can still function without storage, any configuration changes made will be lost upon browser restart.

With its simple yet effective functionality, ReqBlock is a valuable tool for users who want to have more control over the requests made by their browser.