I think everyone on Linux uses it just as the backend inside zathura https://archlinux.org/packages/extra/x86_64/zathura-pdf-mupdf/ https://archlinux.org/packag

I think everyone on Linux uses it just as the backend inside zathura https://archlinux.org/packages/extra/x86_64/zathura-pdf-mupdf/ https://archlinux.org/packages/extra/x86_64/zathura-pdf-mupd... (yes, it's associated with `application/epub+zip` ) and I can tell you that zathura feels very snappy. On Windows mupdf is used by SumatraPDF which also is stupidly fast and supports rendering EPUBs too. EDIT: there's also this https://sioyek.info/ https://sioyek.info/ found thanks to https://github.com/NixOS/nixpkgs/blob/9d13dbb1ef2d0a6a6788d5b6fe4cbd727dd893c5/pkgs/applications/misc/sioyek/default.nix#L11 https://github.com/NixOS/nixpkgs/blob/9d13dbb1ef2d0a6a6788d5...