Tallymark is a web-based application that helps divide living costs between people who live together. It adjusts each individuals rent to compensate for shared expenses such as toilet paper or dish soap, simplifying the process with one check at the end of each rent cycle.

In the summer of 2013, Gene Hua approached me with an idea. Having struggled to find a good solution to share living costs among his apartment, he wanted to build an application that would simplify the process. We began working on Tallymark together. Gene took charge of the design while I wrote up all the code.

Tallymark is written in Python using the Django framework, utilizing some of the many django libraries to simplify the process. The Github repository is available here.

Writing the code and getting everything to work technically was rather trivial. The real challenge came when determining how to best design and implement the application from a user experience standpoint. We thought about how users would use it, stepped through areas that might be confusing for the users, and tried to simplify the experience as much as possible while still providing a rich, interactive (AJAX forms), and functional experience.

For example, we had to think through how users would pay their rent, and how Tallymark would manage expenses from month to month. We settled on a system in which there are archives for each month’s expenses, and the ability to verify that you have paid your fair share of the rent and the past month’s expenses.