World Wide Web
Internet Archive
The archive for all sorts of things that have ever graced (cursed?) the Internet, since 1996
W3Schools
Learn to code HTML, CSS and many programming languages with tutorials
Marginalia Search
Search engine that finds non-commercial websites, with specific filters like 'vintage'
Wiby
Search engine that finds personal websites with simple HTML and CSS
Restorativland
Another wonderful web archive, note the Geocities Gallery
Gifcities
Search for old gifs that were once used in someones Geocities homepage
Warning: flashing lights
Warning 2: NSFW gifs may come up unexpectedly
Flexbox froggy
Game that teaches you CSS flexbox
Dither it!
Image dithering / pixelating tool
Dither Me This
Another image dithering tool
Web Design Museum
Screenshots of old websites, software etc.
The Cheap Web
Cheap = cheap
OldWeb.today
Browse the old web on emulated early browsers
ooh.directory
A list of many blogs sorted by topic
Fancy parts
Cute graphics, mostly teddy bears
HTML color codes
Hex codes for websites
tilde.town
Tildetown is a computer made for sharing. I personally have not joined, but maybe you will?
smallweb
EVEN MORE indie websites
Unicodes
All the Unicode characters, here you can copy and paste any symbol that exists in your computer