Free, multi-format document reader for Windows built for speed and a minimal footprint rather than feature breadth: supports PDF, EPUB, MOBI, CBZ, CBR, FB2, CHM, XPS, and DjVu viewing in one lightweight application with near-instant startup. Popular as a fast default PDF viewer replacement on Windows, particularly among developers who want a no-frills reader without the overhead of a full office-suite-adjacent PDF application.