Figma - Team-based interface design, Figma lets you collaborate on designs in real time.
Figma Component Library - I've curated the best Figma components in one place.
Invision - Prototyping and collaboration for design teams
Facebook Design Resources - A collection of free resources made by designers at Facebook
Sketch - Professional digital design for Mac.
Harvest - Simple time tracking, fast online invoicing, and powerful reporting software. Simplify employee timesheets and billing. Get started for free.