The apps from Andreas Hegenberg are no longer available here.

Legacy versions of his apps (released before February 2018) can be used for free using this license: https://bettertouchtool.net/releases/free_legacy_license.bettertouchtool
However it is not recommended to use these versions as they can contain security and compatibilitiy issues and won't receive any support.

For archival purposes the old legacy source code from early 2018 can be accessed via https://boastr.net/legacy_source_code.zip (MIT license, unpack password: BTT_BST_LEGACY).