5etools is a suite of HTML-and-JavaScript tools for players and DMs of D&D 5e. You can find and download the project on GitHub. Simply download the project as a zip, extract it all to a folder, open the .html files in a browser, and it's ready to go! You can also host your own mirror, or contribute to the project via GitHub. With all the Unearthed Arcana material released, data entry is appreciated!
Classes
Classes.html allows you to quickly browse each of the official classes in 5e. You can also filter for the class' specific subclasses for easier reference, sharing produced URL for quick-access.
Bestiary
Bestiary.html provides a searchable, filterable list of the more than 760 stat blocks in D&D 5e. You can display them and each attack and damage roll can be done in-line with just a click.
Items
Items.html lists the mundane and magical items currently in D&D 5e, allowing quick access to their properties.
Backgrounds
Backgrounds.html lists the official backgrounds in D&D 5e, including those from supplement material.
Feats
Feats.html provides a quick-use list of the feats in D&D 5e, including those from Unearthed Arcana and supplements.
Races
Races.html lists each of the races in D&D 5e, including subraces and variants.
Spells
Spells.html lists all of the official spells in D&D 5e. The list can be easily searched and filtered, and the entries can be shared through the generated URL.
CR Calc
CRcalculator.html provides a verbose, in-depth Challenge Rating calculator, for determining the CR of custom monsters made for D&D 5e.