1. A method comprising: storing a first version of a particular document in storage accessible to a server-side machine; generating, by the server-side machine, an accessibility-enabled version of the particular document based on the first version of the particular document; wherein the accessibility-enabled version of the particular document has one or more accessibility features, which are not present in the first version of the particular document, that facilitate use of a particular assistive technology; storing the accessibility-enabled version in the storage accessible to the server-side machine; receiving a request, from a client-side machine, for the particular document; determining, by the server-side machine, whether to respond to the request with the first version of the particular document or the accessibility-enabled version of the particular document; responsive to determining to respond to the request with the first version of the particular document, the server-side machine sending the first version of the particular document to the client-side machine; and responsive to determining to respond to the request with the accessibility-enabled version of the particular document, the server-side machine sending the accessibility enabled version of the particular document to the client-side machine.
2. The method of claim 1 , wherein generating the accessibility-enabled version of the particular document based on the first version of the particular document comprises: identifying data for the accessibility-enabled version of the particular document from the first version of the particular document; and automatically replacing, in the data for the accessibility-enabled version of the particular document, each instance of each tag of a first set of one or more tags with a corresponding tag of a second set of one or more tags.