| Web-based Development Software | 
          
            | Title | Description | Requirements | 
          
            | 6502js | Emulator for assembling/disassembling 6502 ASM | JavaScript | 
          
            | 8bitworkshop | Learn how to program for 8-bit systems/consoles using an online IDE; "write code and see it run it instantly" | JavaScript | 
          
            | Atari Background Builder | A playfield editor for use with batari, an easy way to create Atari 2600 games with BASIC | JavaScript | 
          
            | BBC BASIC for SDL | BBC BASIC for WASM | WASM | 
          
            | Beebasm | Emulator for assembling/disassembling 6502 ASM for BBC Microcomputers | JavaScript | 
          
            | Bitsy | "a little engine for little games, worlds, and stories" | JavaScript | 
          
            | Bitsy 3D | "a little engine for little games, worlds, and stories"; however, someone tried to make a 3D version | JavaScript | 
          
            | CSS Generator | A tool to quickly generate CSS for text within a box | JavaScript | 
          
            | Decker | Builds on the legacy of HyperCard and the visual aesthetic of classic MacOS | JavaScript | 
          
            | Drawio | Create diagrams online and save/export in various formats | JavaScript | 
          
            | Easy Game Maker | Create an HTML5 game online; reminds me of a simplified mix between microStudio and Scratch; project can be saved for later via a JSON file | JavaScript | 
          
            | FF6Tools | A browser-based editor utility for Final Fantasy VI (Final Fantasy 3 in USA). Current features include a map editor, battle editor, and event editor. | JavaScript | 
          
            | Final Fantasy IV Tweak | An online editor for Final Fantasy IV (Specifically a ROM of Final Fantasy II US v1.1). The current scope is mainly to edit commands. | JavaScript | 
          
            | GB64 | An online Game Boy and Game Boy Color ROM to N64 ROM converter; may be useful in conjunction with GB Studio | JavaScript | 
          
            | GMEdit | An online, open-source code editor for Game Maker GML scripts | JavaScript | 
          
            | Godot v4.3 Web Editor | Create games using the Godot's online web editor (with limitations | WASM | 
          
            | Hasher-js | An online ROM hasher | JavaScript | 
          
            | Imaginary 6502 Emulator / Assembler | Assemble/disassemble 6502 ASM using JavaScript | JavaScript | 
          
            | jswindow | An easy way to use JavaScript to create movable windows on your web page | JavaScript | 
          
            | LÖVE Web Builder | A tool to package, build, and run LÖVE games for the web | JavaScript | 
          
            | microStudio | A free game engine online; program using microScript, Lua, Python, or JavaScript | JavaScript | 
          
            | MyAndroid | Site includes an online Android emulator, an APK runner, and a Cordova IDE with a WYSIWYG/source toggle for HTML; no sign-up required; web browser add-ons available | JavaScript | 
          
            | Pyxel Web Launcher | Launcher tool for the WebAssembly (WASM) version of Pyxel, a retro game engine for Python | WASM | 
          
            | QBjs | An online version of QB64 | JavaScript | 
          
            | Raverie Engine | A pure WebAssembly (WASM) based game engine/editor that aims to recreate the vibe of Flash games | WASM | 
          
            | Ren'Py | A free and open-source visual novel engine | HTML5 and WASM | 
          
            | ROM Patcher JS | Use this online tool to patch ROMs | JavaScript | 
          
            | ROM Usage | A tool for measuring how much room you have left in your GB, GBC, NES, SMS, and GG ROMS | JavaScript | 
          
            | Scratch | "Scratch is the world’s largest coding community for children and a coding language with a simple visual interface that allows young people to create digital stories, games, and animations" | JavaScript | 
          
            | SourceCoder 3 | An online IDE for various TI-83/84 calculators and Casio Prizm, fx-9860, or fx-9750 | JavaScript | 
          
            | Text Tools | A LOT of text-related tools; could be good for both documents and scripts | HTML5 | 
          
            | TGE (Top Gear Editor) | Use this to edit "Top Gear" for the SNES | HTML5 | 
          
            | Tiny BASIC | An online Tiny BASIC interpreter | HTML5 | 
          
            | Tuesday JS Visual Novel Engine | An online visual novel engine; you can save progress as JSON file or build as HTML, ZIP, or pack everything as Base64 in a single HTML file | JavaScript | 
          
            | TurboWarp | "...the better version of Scratch with dark mode, addons, a compiler, and a lot more"; there is also a desktop version | JavaScript | 
          
            | Twine | Write interactive stories and presentations | JavaScript | 
          
            | ugBASIC | A way to test simple code meant for ugBASIC but online, though it can build; ugBASIC provides a way to create games for several 8-bit microcomputers | JavaScript | 
          
            | ViewJS | Use this tool to help your website visitors view Open Document Formats like ODT, ODP, and ODS and also PDF documents online | JavaScript | 
          
            | ViperCard | An open source re-creation and re-imagination of 1987's HyperCard | JavaScript | 
          
            | Watabou's Procgen Arcana | Online tools for randomly generating top-down, map-like images of realms, cities, villages, caves/glades, dungeons, and dwellings; great if having a hard time coming up with places for a role-playing game | WASM | 
          
            | WebGM | Create WebAssembly (WASM) games online using a GameMaker-like interface | JavaScript/WASM | 
          
            | ZQuest Classic | Technically meant to play Zelda-like games; however, there is also an editor; there is also an offline editor | WASM |