Droplist is a simple to-do list App which Andrew McKinney released a couple of weeks ago. Since then, it has taken off and become one of the top selling to-do list apps and is ranked in the top 25-50 in the Productivity category. Below, McKinney explains how 37signals ideas helped him create the product.
Under-doing the Competition
Apps like Things and Omnifocus are packed with to-do list functionality, and share a pricetag to reflect this. Instead of going for this all-encompassing functionality, I aimed at underdoing their approaches, and created a simple-yet-powerful to-do list app with a low price. I took the approach of removing functionality rather than adding it. For example, I did away with prioritization, favoring simple sorting instead. I also concentrated on really understanding how people create lists which brings me to the next 37signals lesson...
Nailing the basics
I took a long look at what my competitors approaches to to-do list apps and compared this with how people naturally create lists in real life. By watching how others created lists, as well as observing my own habits I learned that to-do lists are more often than not created in haste. They are scratched out within a few minutes or even seconds, and do not have time for lots of button tapping (like other to-do apps). My design was geared toward letting users quickly type out a list (hitting "return" to create a new item) or copy-paste a list from email or web. I wanted to ensure that this list-entry was as gratifying as possible, and reviews have revealed that this is its killer feature alongside Dropbox sync.
I built this app part-time on about 10 hours per week. It took me about two months to complete this project from start to finish. As both David and Jason mention, this limited amount of time each week focused my development efforts on nailing the core of my design. When it came to a sync service, I looked at building my own service, but realized this would take too long. Instead, I looked at using something that would allow people to edit their lists outside of the App. Dropbox became a natural fit because of its excellent integration with the iPhone, as well as it's "always there" approach to file sharing.
Over the next few weeks I will be releasing an iPad universal update and improving many of the experiential features of the App. With any luck I'll be able to move from part-time on this App to full-time within the near future.