Marvel

Marvel is a UK-headquartered design platform for wireframing, prototyping, user testing, and developer handoff. Founded in London in 2013, it serves teams from startups to Fortune 100 companies. Browser-based with no downloads needed. Features include drag-and-drop design with millions of assets, interactive prototyping for any device, built-in user testing, and automated design specs with CSS, Swift, and Android XML code generation. Free tier available with no time limits.