So I recently started playing as a DM, maybe these links will be helpful for someone :)
Dicecloud  - The only tool your players will need. I absolutely love Dicecloud. It’s the perfect place to make your character sheets, and if you need any help with it (it can be a bit confusing at first), then there’s an active Discord server with tons of people who are more than willing to help!
Dicecloud Spell Manager  - Handy tool that lets you add any and all official spells to a character.
5eTools  - I use this page only for the races resource, but there’s lots more to discover there!
DND 5e Wikidot  - This one I use for classes, sub-classes, backgrounds, and feats.
D&D Spells - Every single official spell is on that page, and you can set different filters for classes and such
100 Warm-Up Roleplaying Questions for Players - to help new(ish) players get to know their characters!
Azgaar’s Fantasy Map Generator - Great tool for creating a world map. There’s so many useful features that you can use.
DndSpeak - I love, love, love this page so much!! There’s so many different generators and lists, here are a few examples:
Ghost’s Unfinished Business
100 (Weird) Quest Rewards
100 Prophetic Dreams That Mean Nothing
100 Interesting Shopkeepers and Merchants
100 Guilds to Liven Up Your World
5e Magic Shop - A generator that creates an inventory for a magic shop. Really useful for getting prices and such. This page also has other tools that may be useful!
Donjon Encounter Size Calculator - This one is, obviously, for seeing how much my players can theoretically handle when they’re not killed by random owlbears. This is really useful for new DMs ^^
For creating notes I use a Onenote notebook. Mine is shared with my players, and the sections that have “confidential” information are locked with a password. My players have also created their own sections where they make their own notes. This way, all of our notes are in one place.
Okay, that’s it for now. If I remember or discover any other, I’ll add them to the list!
(Last updated 3. July 2020)