CookieSync: syncs cookies to localhost — Roel Noten

This is an add-on which copies cookies to localhost.

This addon monitors all incoming cookies from a user defined hostname regex and matching a user defined cookie name regex to copy them to the http://localhost domain.

It's primary here for developers that have code running on their localhost which connects to other services and need access to their cookies. The typical use case is a third-party login flow. In production the developer's code wil run on the same domain as the other services and have access to the cookies they set.
But when code is running on localhost (during development), those cookies are not accessible in the browser. This add on makes those cookies available on localhost, so available to the developer's local code.