Presently the ESI specification contains four areas of definition. Listed below are specifications for the Edge Side Include language itself, the use of HTTP headers to extend Web infrastructure, an invalidation protocol for content management, and a JSP tag library for easy integration with J2EE compliant systems. Further specifications will be added as the definition of ESI continues to evolve.

ESI Language Specification
This specification defines ESI 1.0, the Edge Side Includes language, which allows content assembly by HTTP surrogates, by providing an in-markup XML-based language.

Edge Architecture Specification
This document defines the Edge Architecture, which extend the Web infrastructure through the use of HTTP surrogates - intermediaries that act on behalf of an origin server.

ESI Invalidation Protocol
This specification defines the ESI Invalidation Protocol, to allow for tight coherence between origin serves and surrogates (also know as "Reverse Proxies").

JESI Tag Library Specification
The Java ESI tag library is intended to be the convenient JSP application-level interface to the ESI tags for web caching functionality. Its purpose is to facilitate the use of ESI tags within a JSP application.