13. A computer system comprising: one or more computer processors; an interface to receive, from client computing devices, requests for first electronic documents that are hosted on separate computer systems that are distinct from the computer system; a request processor programmed to obtain, from the separate computer systems, the first electronic documents; a parser programmed to: (i) determine whether or not to process each first electronic document based on an identity of the separate computer system upon which it is hosted, and (ii) when the parser determines to process the first electronic document, identify one or more portions of particular first documents of the first electronic documents that certain of the client computing devices are not configured to interpret or execute, the one or more portions comprising interpreted language elements; an interpreter programmed to convert, in response to the identification by the parser, the one or more portions of the particular documents into one or more portions of replacement content that is of one or more content types that the certain client computing devices are configured to interpret or execute; a document generator programmed to generate, particular second electronic documents that include i) the one or more portions of replacement content and ii) other portions from the particular first documents that the client computing device is configured to interpret or execute; and a response formatter programmed to provide: (i) the first electronic documents to the client computing devices as responses to the requests from the client computing devices when the parser determines to not process the first electronic document, or (ii) the particular second electronic document to the client computing devices as responses to the requests from the client computing devices when the parser determines to process the first electronic document.
13. A computer system comprising: one or more computer processors; an interface to receive, from client computing devices, requests for first electronic documents that are hosted on separate computer systems that are distinct from the computer system; a request processor programmed to obtain, from the separate computer systems, the first electronic documents; a parser programmed to: (i) determine whether or not to process each first electronic document based on an identity of the separate computer system upon which it is hosted, and (ii) when the parser determines to process the first electronic document, identify one or more portions of particular first documents of the first electronic documents that certain of the client computing devices are not configured to interpret or execute, the one or more portions comprising interpreted language elements; an interpreter programmed to convert, in response to the identification by the parser, the one or more portions of the particular documents into one or more portions of replacement content that is of one or more content types that the certain client computing devices are configured to interpret or execute; a document generator programmed to generate, particular second electronic documents that include i) the one or more portions of replacement content and ii) other portions from the particular first documents that the client computing device is configured to interpret or execute; and a response formatter programmed to provide: (i) the first electronic documents to the client computing devices as responses to the requests from the client computing devices when the parser determines to not process the first electronic document, or (ii) the particular second electronic document to the client computing devices as responses to the requests from the client computing devices when the parser determines to process the first electronic document. 17. The computer system of claim 13 , wherein the interpreter converts the one or more portions of the first electronic documents into the one or more portions of replacement content by: executing or interpreting the one or more portions of the first electronic documents, wherein the execution or interpretation of the one or more portions of the first electronic documents causes information that is included in the one or more portions of replacement content to be generated.