Adventure Lookup – Categorized database of published adventures.
Dice Roller – Online dice roller.
D&D Beyond – Official “digital resource”. Features a player character builder, content library, and homebrew creation tool. Anything beyond the Player’s Handbook content must be purchased.
Bogsy’s Magical Scrolls – Mobile friendly website to lookup and manage spells.
Browser Based 5e DM Screen – Online “DM Screen” reference.
Cheat Sheets – Collection of cheat sheets. The combat sheet is particularly useful to hand out to your players.
Damage Type Descriptions – Cheat sheet of descriptions by damage type.
OneNote – A powerful, cross platform note management tool.
EverNote – An alternative to OneNote.
RPGBuddy – Track your character, initiative, and custom encounters!
GM Binder – A tool to create and manage your game documents.
Aglet Timekeeper – Simple, browser based time tracker.
Player Interest Survey – Gauge what your players are looking for in their tabletop experience.
The Same Page Tool – A questionnaire that can help create a cohesive campaign with players and DMs all being on the same page.