JavaScript

Splitting.js

JS library to iterate through every instance of class (or to break a single div into multiple divs) to be able to animate them individually. Useful for animating text char by char or delaying each item in a list.

Alpine.js

Simple interactivity directly in HTML

Manage HTML DOM with vanilla JavaScript - HTML DOM

Do you really need a framework library?

Vanilla JS Toolkit

A collection of tools and snippets for working with JavaScript.

CSS

Native Elements

CSS Superpowers for HMTL elements. Visual Great for quickly making a basic (usually single page) site.

I found this on Twitter via @prathkum

Full bleed images in a blog layout

CSS Grid full-bleed layout tutorial via Josh W Comeau

CSS Shadow generator

CSS Shadow Palette Generator via Josh W Comeau

Highlight images without alt text

CSS to Highlight any image on your site that doesn’t have alt-text. Via @addyosmani on Twitter.