Lossless web-based editing for XML documents is provided. A method for editing a document over the Internet includes receiving a request on a server over the Internet to edit a document. The server extracts content from the document to form a modified version of the document in XML format and transmits the modified version of the document to the client over the Internet. The client edits the modified version of the document using a web browser editor and transmits changes to the modified version of the document to the server. The server merges the original document and the changes made by the client to form an edited version of the document that updates the document with the client changes and that leaves the remainder of the document intact.