OrCAD is a proprietary collection of software for electronic design automation (EDA).
OrCAD's integrated development environment (IDE) focuses on tools for schematic capture, PCB layout, and generating files from them in the standard for manufacturing PCBs -- Gerber format and Excellon drill format. It also has tools to create a bill of materials (BOM), do design rule checking (DRC), run SPICE simulation, develop FPGA firmware, etc.
Other EDA software comparable to OrCAD: KiCad gEDA EAGLE
The free "OrCAD Viewer" is two applications: "Capture Viewer" is a free viewer for schematics in OrCAD format (".opj" and ".dsn" extensions). "PCB Editor Viewer" is a free viewer for PCB layouts in OrCAD format (".brd", ".dra", and ".mdd" extensions).
official site: [FIXME:]
OrCAD Viewer: https://www.parallel-systems.co.uk/wp-content/uploads/2022/01/Free-Viewers.pdf