| WASM-4 | WebAssembly-based fantasy console running cartridges in browser or native runtime. | both |
| Warajevo | DOS ZX Spectrum emulator famously developed in Sarajevo during the Bosnian War. | downloadable |
| WasmBoy | Game Boy and Game Boy Color emulator written in AssemblyScript and compiled to WebAssembly. | online |
| Watara Supervision | The Potator emulator for the Watara Supervision, compiled to WebAssembly to run in the browser. | online |
| WebMSX | HTML5/JavaScript MSX emulator that runs in the browser and installs as a web app. | online |
| Wernsey CHIP-8 | CHIP-8 and SUPER-CHIP interpreter, assembler and disassembler written in C. | downloadable |
| Whitespace Interpreter | An authored, in-browser Whitespace interpreter with a live token view, stack, heap and a single-stepping debugger. | online |
| Williams Arcade | The Williams arcade hardware (1982, Motorola 6809), booting Robotron: 2084 in the browser with an in-frame 6809 debugger. | online |
| Win994a | Free Windows TI-99/4A simulator by Cory Burr that runs console BASIC and over 200 cartridges. | downloadable |
| WinAPE | Popular Windows emulator of the Amstrad CPC range with a built-in Z80 assembler and debugger. | downloadable |
| WinArcadia | Multi-machine emulator for Signetics 2650-based consoles and computers such as the Emerson Arcadia 2001 and Interton VC 4000. | downloadable |
| WinFellow | Long-running open-source Amiga emulator for Windows optimized for early-model games and demoscene. | downloadable |
| WinUAE | The most accurate Commodore Amiga emulator for Windows. | downloadable |
| WinX68k (Keropi) | Pioneering Sharp X68000 emulator for Windows by Kenjo, also known as Keropi. | downloadable |
| WindEmu | A hardware-level emulator for the Psion Series 5mx (EPOC32). | online |
| WineVDM (otvdm) | A compatibility layer and emulator that runs 16-bit Windows 1.x through 3.x applications on 64-bit Windows. | downloadable |
| WonderSwan | Bandai WonderSwan and WonderSwan Color emulator, the Mednafen (Cygne-derived) core compiled to WebAssembly, with a live V30MZ debugger. | online |