There are literally thousands of sites that will give you free stuff to help you play. Below are a few of my favorites.
dndadventuresforkids.com – A site dedicated to creating and distributing free D&D adventures for kids.
OrcPub2.com – This is a very easy to use site that allows you to create, download, print and share characters and other D&D 5e content.
5emagic.shop – Need a quick magic items shop for your adventure? You are just seconds away with this site.
Donjon – Need a quick random dungeon generator? It doesn’t get faster or easier than this. This generator creates old-school dungeons, which are great for dungeon crawls.
dndbeyond.com – D&D Beyond is a web app that lets players create and store characters, peruse items and monsters and consult digital D&D tomes, among other things. It’s a “digital tool set” for the game. Accessing premium content does cost extra. In some cases, it is cheaper to buy the books online.
dmsguild.com – The DM’s Guild is an online resource for free and low cost gaming materials, modules, adventures, digital books, maps, and much more.
tools.goblinist.com – Need a quick random encounter? It doesn’t get much easier or faster than this.
Nerdarchy – For Nerds By Nerds. Tabletop RPG Enthusiast with a particular soft spot for Dungeons and Dragons.