I love dice, I love fiddling with game design, and I love simple tools that make things easier.
At the nexus of those three things sits AnyDice.
Developed by Jasper Flick, AnyDice calculates the probability of each possible result for just about any die roll. (I say “just about,” but it’s never let me down.)
Need the probability curve for d8+d10, one of my favorite rolls for building random encounter tables? It can do that.
Funky dice for DCC RPG? Sure. Dice that don’t actually exist, like d67s? You bet!
AnyDice isn’t a die roller in the sense that it rolls dice and tells you what you got, like the Crawler’s Companion. It’s all about the odds.
Although they wound up being percentile tables in the end, I used AnyDice extensively while I was designing my DCC RPG wilderness encounter tables. I used it to calculate the odds for Hexmancer rolls, to make sure the percentages lined up. Almost every post I’ve written involving math and dice, like comparing dungeon stocking in OD&D and Delving Deeper, was written with AnyDice open in another browser tab.
Writing this post made me realize just how often I use AnyDice without thinking about it, so I hit the “Please Donate!” button and made a contribution.
Math isn’t my strong suit, but AnyDice enables me to use math to do things I enjoy without beating my head against them. It’s a stellar tool for game design, and one I recommend bookmarking and using often.
 It has a die roller in the traditional sense built in, but it’s in beta and the functionality — unlike the core of AnyDice — is pretty limited.