Web development
- HTML Cheat Sheet - as the name suggests. css and js also available.
 
Web tutorials
- w3schools - referenced religiously. learn to code in several programming languages
 - sadgrl.online & create.dvdv.kim - beginner neocities tutorials
 
Layouts and layout builders
- Sadgrl's Layout Builder
 - PetraPixel's Layout Generator
 - 11ty (Eleventy) - static site generator, tutorial here
 
Code snippets
- RV's DHTML web-scripts - fun js/DHTML effects
 
Code editors
- personally, i use Visual Studio Code. offline editor with a browser version, customisable supporting many extensions (i had a lot of fun with this).
 - Brackets - customisable, beginner friendly, centered around html/css
 - Notepad++
 
Other code editors (i haven't tried them, so you'll have to check them out on your own)
Useful tools
- Catbox & File Garden - file hosting
 - Dither Me This & Dithermark - dither your images
 - generator.lorem-ipsum - lorem ipsum in different scripts (includes artificial languages & morse code!)
 - viewportsizer - shows you your screen size
 - Optimizilla - image compressor
 - dead link checker
 - Backlink Checker
 - Encode your email address
 - Cemetech + Casio Prizm (fx-CG) Programs and Games
 
Less useful but fun tools
- BitFontMaker2 - make your own font
 
Site decor
Backgrounds
- hekate2's background archive, organised by color/theme
 - hekate2's background generator
 - sadgrl.online's tiled background archive
 - fancyparts.com - cutesy patterned backgrounds
 - Paper Tiles - tiled wallpaper backgrounds
 
Graphics, blinkies, buttons, stamps
- blinkies.cafe - blinkie generator
 
 -
                    identity buttons- GifCities - geocities gif search
 - Glitter-Graphics.com - graphics, layouts, glitter text (has backgrounds too!)
 
Other
- GifyPet - build a pet
 - tamaNOTchi - virtual "tamagotchi" to put on your website!
 - imood - display your mood
 - Pollcode - create polls
 - FC2 Counter - count site views (accesses)
 
Entertainment
- WindowSwap - swap windows with someone in the world
 - Dragon Cave - adopt and raise dragons
 - radio.garden - listen in to radio stations from around the world
 
Language learning
- DeepL - pretty good translator
 - LangCorrect - write and get it corrected by natives (the catch is you have to correct entries in your native language as well).
 - Clozemaster - learn vocabulary through fill in the blank sentences