Embodiments of the present invention provide a method, system and computer program product for Web storage optimization and cache management. In one embodiment, a method of client side cache management using Web storage can include first registering a client browser session in a content browser as a listener to events for Web storage for a particular domain. Subsequently, notification can be received from the content browser of an event of a different client browser session associated with the Web storage. For instance, the notification can result from the different client browser adding a new cache entry to the Web storage, or from the different client browser periodically at a specified time interval indicating a state of one or more cache entries in the Web storage. Finally, in response to the notification, a cache entry in the Web storage can be invalided such as through cache entry removal or compression.