150 hours (~ 3 weeks)
Huh. A huge project (...on my standards). I decided to produce a time management application for desktop use. Primary target group: myself. I desperately needed a time logging app that could be easily used straight from desktop environment and that would keep tracking my activities in the background.
Later I decided to try and sell this desktop application commercially to other people.
Technically this project is my greatest achievement. App works well, UI looks good, statistics are always generated from raw data (event sourcing-principle) so they are always automatically up-to-date. Internally it has a beautiful data-driven flow, which is directed from separate OS process towards UI process. All internal calls crossing layer boundaries return Promises, and excellent T3.js framework takes care of managing control flow from UI to application's heart.
Very demanding project all in all. Happy I got it to current state (work still goes on, although sporadically).
Commercially the app has not taken off yet. We will see how that goes. No matter what happens, this piece of software is currently the one I am most proud of. By a huge margin - nothing I've produced earlier comes nowhere near.
Check out the project info site: aikavahti.nollaversio.fi