Composition of templates using transclusion that guarantee a valid HTML document

A system, method and computer-readable medium for composing a valid HTML document using template transclusion. A system includes a memory configured to store a transcluded template file, the transcluded template file includes a transcluded template and a transcluding template file, the transcluding template file including a transcluding template, the transcluding template including credentials to the transcluded template. The system also includes a template building module configured to build a transcluded template object from the transcluded template and a transcluding template object from the transcluding template, where the transcluded template object and the transcluding template object generate a valid HTML document that is sent for display on a browser.