A compressed file produced by a server is used for updating a hypertext markup language (HTML) document cached on a client computer with changes so that it is identical to a changed HTML document stored on a server computer. Typically, when a user requests access to the HTML document on a server computer corresponding to the cached HTML document on the client computer, the cached HTML document is opened and processed by a client agent software module to produce a macro name file and a macro definition file. A checksum or macro name is determined for each construct or list in the cached HTML file. Each macro definition in the macro definition file is a concise content of the construct or list comprising a different portion of the HTML file. The client agent transmits the uniform resource locator (URL) for the site from which the cached HTML document was obtained and appends the macro name file (assuming that the server computer hasn't already generated the macro name file). A server agent at the server site produces a macro compressed file in which the macro name for each section that is unchanged is included, along with the actual contents of those constructs or lists in the HTML file stored on the server computer that have changed. The macro compressed file is transmitted back to the client agent for expansion and to refresh the HTML file that is cached on the client computer. The updated HTML file can then be displayed using the browser on the client computer.