Seer

Seer is a fast file opening tool. In a few minutes it is able to open any file e.g. images (PSD and AI), audio and video, ZIP and RAR archives, text files, source code (with syntax highlighting), PDF documents, MS Office documents, MarkDown files or folder contents. Its main feature is that it does not modify associated (default) programs, as it does not open files by double-clicking, but by selecting the file and pressing the space bar, in its own - very minimalistic - windows. The tool only supports reading files, not writing and modifying them.