Q3Edit, a web‑based editor for Quake III Arena map files, lets users create, modify, and launch maps directly in a browser. The tool runs on TypeScript and WebGL2 and compiles .map files using WebAssembly built from id Software’s original q3map compiler. It includes OpenArena assets and requires WebGL2 support, enabling one‑click execution with ioquake3. The interface features a four‑view layout and tools for brushes, patches, constructive solid geometry, and terrain editing. No original game files are needed, and the compiled maps can be played instantly in the browser. Map editing for Quake III has traditionally required desktop software, but Q3Edit demonstrates how modern web technologies can replace those workflows. The project demonstrates the ability to edit and run Quake III maps in a browser, potentially expanding community map creation capabilities.