Sketch is an interface design toolkit made of a native Mac editor and a web app. Designers draw icons and app screens with a vector editor on an infinite canvas, starting from templates, frame presets, and shared libraries, and can keep working offline.

Prototyping - build clickable prototypes with Smart Animate, overlays for modals and menus, hover, press, drag, and swipe interactions, and scroll areas, then test in a browser or on iPhone and iPad.
Collaboration - share documents or password-protected previews, comment in threads, co-edit in real time, and keep files and libraries in a team Workspace.
Developer handoff - developers inspect files, download assets, and export design tokens for free.
AI connection - point an AI client at a frame through MCP to build it out in code.
iOS app - view and mirror designs on iPhone and iPad.

It is used by product designers and teams designing apps and websites, from freelancers to large companies. The Mac editor requires macOS Sequoia or newer; pricing details are on the pricing page, and Sketch is free for education.