1. A system for generating a platform-independent document comprising: a database system implemented using a server system, the server system including one or more processors and one or more storage devices, the database system configurable to implement a document-rendering service configurable to: receive a request to generate a platform-independent document based on a renderable web document, the request including markup language content for the renderable web document; provide the markup language content to a rendering engine of the document-rendering service, the rendering engine being configured to: parse the markup language content, generate one or more resource requests for resources identified in the parsed markup language content, and communicate the one or more resource requests; intercept the one or more resource requests communicated from the rendering engine; communicate the one or more intercepted requests, or one or more requests based on the intercepted requests, to retrieve resources identified in the one or more intercepted requests; receive resources retrieved based on the communicated one or more intercepted requests, or the communicated one or more requests based on the intercepted requests; provide the received resources to the rendering engine, the rendering engine being further configured to generate the platform-independent document based on the markup language content and the provided resources; and provide the generated platform-independent document for communication to a remote computing device.