PCjs is an open-source project that uses JavaScript to emulate vintage hardware and software from the 1970s and 1980s. It allows users to experience the computing era of their youth, complete with slow CPUs, low-resolution displays, and primitive sound effects, all within a modern web browser.

Over time, PCjs has expanded its collection to include emulations of IBM PC Compatibles, Minicomputers, Programmable Calculators, Terminals, and Arcade Games. The project aims for modest preservation efforts, inviting contributions via its GitHub repository. Users can explore public domain software and shareware like PC Disk Magazine (1983) and PC Magazine Utilities (1987), and interact with hardware and software such as the TI-57 Programmable Calculator (1978) and Space Invaders (1978).

The PCjs Explorer provides access to a vast array of historical combinations, accompanied by documentation. Notable emulations include classic operating systems like CP/M-86 (1983) and early versions of Microsoft Windows (1985), alongside influential software such as Visi Calc (1981) and Lotus 1-2-3 (1983). The collection also features popular games like The Oregon Trail (1991) and Wolfenstein 3D (1992).