I researched in this SE and I found this and this, but this is not what I am looking for. I have various computers so 1 time tracker for 1 desktop doesn't work if I need Linux for some task and each computer is old (and the software recommendations look like a high-memory footprint).
Or for example, I use one computer for programming, one for data visualization, and one for research and communication. So I think the better software is one that takes screenshots every 10 minutes on each computer a desktop software like Greenshot, but in this case, take a screenshot and save it automatically while I am working.
This is enough for my clients to check my progress and the time spent on the task.
I am looking for a freelance recommendation because I can't trust the Internet and the software may be some time tracker that has malware and takes my money. Does anyone know?