Frontend Mentor provides design files and specifications for realistic front-end projects, from simple cards to multi-page layouts with interactive components. You build the site yourself using whatever tools you prefer, then compare your result to the design. The challenges include starter files, style guides, and asset packages. Solutions from other developers can be browsed for reference.

It fills a gap between tutorials that hold your hand and open-ended projects with no direction. The challenges mirror what you would encounter in a real job: responsive layouts, accessibility considerations, and design fidelity. For junior developers building a portfolio, working through several challenges gives concrete examples to show employers.