Balsamiq - Balsamiq. Rapid, effective and fun wireframing software.
WatchMaker Watch Face - With WatchMaker you get access to 1000's of stunning watchfaces and a designer to build your own.
Invision - Prototyping and collaboration for design teams
Willow - Willow is a lightweight logging library written in Swift.
Zeplin - Collaboration app for UI designers & frontend developers
Huawfaces - Huawfaces provides a large number of WatchFaces for installation Huawei Watch GT, GT2, GT2E, and GT2 Pro.