1. One or more computer-readable storage media comprising computer-readable instructions that, when executed by a processor, cause a computer-controlled device to perform a computer-implemented method for searching a page-based markup document for an input search string, the method comprising: receiving, at the computer-controlled device, at least one search request including the input search string from a user; analyzing, by the computer-controlled device, markup elements defined for a plurality of pages within at least one source document, wherein the markup elements comprise at least one of text, drawings, formatting, or images, and the source document is an unrendered version of the page-based markup document; determining whether the markup elements for the pages may include at least part of the input search string; selecting at least one page from the plurality of pages as a candidate page for rendering, the selecting in response to determining that the markup elements for the page include at least part of the input search string; rendering the at least one candidate page; determining whether the search string occurs in the rendered candidate page; indicating at least one location within the rendered candidate page at which the search string occurs; and outputting search results that indicate where the input search string occurs in the rendered page based on the source document.