Visily - The easiest and most powerful wireframe software for agile teams.
Adobe XD - Adobe XD is an all-in-one UX/UI solution for designing websites, mobile apps and more.
PSD to Sketch Design Converter - Convert a Photoshop design to a layered Sketch file for free
Abstract - A secure, version-controlled hub for your design files
Zeplin - Collaboration app for UI designers & frontend developers
Figma - Team-based interface design, Figma lets you collaborate on designs in real time.