How do you organize your digital library?

Hello everyone!

*(If you want to skip the context and just answer the questions, feel free)*

(Also, I made a similar post in r/libgen, sorry if you come across it more than once)

I’m a master’s student in Communication Sciences and Human-Computer Interaction.

I am currently working on a UX (user experience) project about methods of organizing reading, research and notes, especially in terms of academic bibliography and notes. In particular, I have a lot of interest in the use of open source software. As a long time user of scihub and a strong partisan of open access, I really want to include other users in my research.

Right now, I am still in the exploration phase, and I want to approach the topic by gathering some real use case information. So, if you could take the time to answer the following questions as briefly or with as much detail as you want (it will hardly take more than 10-15 minutes anyway), I would really appreciate it!

1. What is your preferred system to organize your bibliography?
2. What is your preferred system to take and store research notes?
3. What are some aspects/features of your current bibliography and note systems that made you settle for them?
4. Have you tried other systems (e.g. reference management or note-taking software)?

4.1. If yes, what were the main downsides that made you switch to another system?

Thank you for your time!

*(I know these questions might be quite naive, but I am trying out a new research method. Also, apologies if my English is confusing sometimes, it is not my native language)*