Balsamiq - Balsamiq. Rapid, effective and fun wireframing software.
Notebook.ai - A smart notebook that grows and collaborates with you
Invision - Prototyping and collaboration for design teams
Moleskine Smart Notebook - Turn hand-drawn sketches into fully workable vector files
Zeplin - Collaboration app for UI designers & frontend developers
World Anvil - World Anvil is a worldbuilding tool for Authors, Storytellers and worldbuilding lovers.