Do Chrome and Firefox share a browser cache?

Question

So I was having a problem with some stuff on SO not working that was similar to this post on Meta which recommended clearing the browser cache.

Now it wasn't working in both Chrome and Firefox and I had never logged in to SO on FF before today so FF couldn't have cached the file itself. Tried hitting refresh multiple times and even tried Ctrl-F5 with no luck.

I cleared the browser cache in Chrome only, and after that it started working on both Chrome and FF. How could clearing the cache of one browser affect the other?

Solution

The browsers do not share a cache, but plugins might. Like Adobe Flash keeps cross-browser history and "local shared objects", which can be used in a cookie-like way. Clearing a cache in a browser usually does not remove the information stored by such plugin.

Comments

[Mau]

Had issues on FF today as well, can't figure it out. IE works fine, cleaning FF doesn't help (even its DNS cache via plugin).

[Koder101]

I see this in Windows between Chrome and FF. They do share the cache and I don't know how to to stop it.

[Arjan]

Server-side sessions like those maintained by $_SESSION often rely on cookies, and cookies are not shared across browsers. Hence, each browser would have its own session.

[MicroMachine]

"Like Adobe Flash keeps cross-browser history" sounds like a security issue

[Rafael Aguilar]

"Like Adobe Flash" sounds like a security issue.