Asm Editor runs M68K, MIPS, RISC-V, x86, and Z80 assembly entirely in the browser, backed by WASM interpreters ported from real emulator projects like s68k and Specy’s own MIPS and RISC-V simulators. Step or undo instruction by instruction, set breakpoints, and inspect registers and memory as they change; a built-in screen, keyboard, terminal, and mouse let programs actually draw and take input rather than just print. Free, works offline, and cited in a 2026 IEEE EDUCON paper on teaching assembly.