Build in memory datastore, queuing systems, file storage etc then make them run in a distributed environment and keep adding new features as per your interest

Where can I get some specifications to begin with?

Software Developer

What specs do you want? It's put and get APIs. Add your own restrictions. It's a side project afterall

Look up udit agarwal queue system on YouTube. Implement and host it.

Software Engineer

What kind of side projects can backend engineers include in resume/ work on like during weekends?
I don't wanna know machine learning model and layer of API

What kind of side projects can backend engineers include in resume/ work on like during weekends?
I don't wanna know machine learning model and layer of API over it. Thats something I already worked in college.

If someone already working on something and need partners, ping in comment. We can connect.

Backend Engineering side projects