Documents for webMethods 11.1 and newer are being hosted on IBM Docs . These pages often include a "PDF" option in the side menu for specific chapters or entire guides.
For webMethods 10.15 and earlier versions, the Software AG Documentation website remains the current repository. You can select specific versions via a pull-down menu and often find direct links to PDF versions of the "Webhelp" content. webmethods documentation pdf
Official documentation is categorized by version and product area. You can find comprehensive PDF guides at the following locations: Documents for webMethods 11