Disclosed embodiments are directed at systems, methods, and architecture for providing auto-documentation to APIs. The auto documentation plugin is architecturally placed between an API and a client thereof and parses API requests and responses in order to generate auto-documentation. In some embodiments, the auto-documentation plugin is used to update preexisting documentation after updates. In some embodiments, the auto-documentation plugin accesses an on-line documentation repository. In some embodiments, the auto-documentation plugin makes use of a machine learning model to determine how and which portions of an existing documentation file to update.