An illustrative embodiment of a computer-implemented method for generating secured documents using a source template is disclosed, in which a computer system receives the source template; converts the source template into a secured template comprising user-modifiable extension points, wherein the secured template is not user-modifiable outside of the user-modifiable extension points; receives a user input comprising one or more user-indicated modifications at one or more of the user-modifiable extension points; modifies the secured template into a custom document with modifications to the one or more user-modifiable extension points in accordance with the one or more user-indicated modifications; and transforms the custom document into a secured custom document that comprises the modifications to the one or more user-modifiable extension points and that is in a format that is executable using a source schema associated with the source template.