Zac Cohan

Zac Cohan is a software developer best known as the creator of Soulver, the notepad calculator that works out answers as you type ordinary words and numbers. He runs Acqualia Software, the small studio that has published Soulver for Mac, iPad and iPhone since the mid-2000s.

Cohan started working on Soulver in 2005 with co-founder Nik Youdale, when the two were engineers living in Australia. They found it strange that calculator apps on the Mac still imitated physical calculators, and their breakthrough was a simple layout: a notepad on the left and a live answer column on the right. Acqualia, which describes itself as crafting apps since 2004, shipped Soulver for Mac, then Soulver for iPad around 2010 and for iPhone in 2013, alongside another Mac app, Picturesque.

The business was not always easy. Cohan has described 2014 as the hardest year, when a one-time-purchase model did not bring in enough sales and the first serious copycat appeared, and he stepped away for a few years. Youdale later left for Canva. Cohan returned to Soulver full time in 2018 and rebuilt it: Soulver 3 launched on the Mac at WWDC 2019, followed by iPad and iPhone versions, adding variables, line references, date and unit maths, subtotals and automation. He also released SoulverCore, the app's calculation engine, as a Swift framework for other developers.

In June 2026 he shipped Soulver 4, the first paid upgrade in seven years, with more than 50 new features, a universal purchase across Mac, iPad and iPhone and a $59 one-time price, plus availability through Setapp. He still answers customer email himself.

Cohan is a model of the patient indie: nearly two decades refining one idea, borrowing concepts from spreadsheets, programming and code editors to make everyday maths feel like writing.