Gravacacher is very simple and lightweight caching server designed for one specific purpose: to cache avatar images from services like www.gravatar.com, which provide "globally recognized avatars". Typically, Gravacacher will be deployed on sites that host blogs or forums which depend on gravatars. Gravacacher supports a security mechanism that allows it to answer only queries made via URLs generated by your server software, such as blog or forum engines, permanent cached entities, and both positive and negative TTLs when caching.
