I built TaskTXT.com based on my experience timing my tasks. I found that committing to a task before I start helps with my focus, and guessing how long it will take, then timing it prevents me from wanting to give in to distractions because I'm "on the clock".
Video Overview: https://www.youtube.com/watch?v=HOYO0c_D6w0
There's also a Mac app which you can download here: https://dl.todesktop.com/22080519n9z1jew/mac
Video overview of the Mac app: https://www.youtube.com/watch?v=qMs-V5v5gZY
But I didn't want the tool to be distracting, so its based on plain text. That means the UI is very familiar and you can use it for generic notes in any structure you like. When you work in TaskTXT you are working directly on its data format, I made a video about this concept here: https://www.youtube.com/watch?v=kZdBgVZn5NI
I think this tool is uniquely suited for programmers, so I'd be interested to hear any feedback about the product, or its viability as a business.