How to make a portfolio for yourself?

Question

Freelance

How to make yourself a normal portfolio if you mainly work on the backend and projects that are more isolated from the outside world, such as integration systems for some companies.
That is, if you want to switch to freelancing, but let's say you have experience, in order to prove it to the customer, you need to show examples of projects - what you worked on, etc. and how to do it?

Answer 1

Ask to be given a test task, or if you have time / desire, participate in open-source projects

Answer 2

Github decides

Answer 3

For clients, problem solving is important. If you can, describe the tasks of clients and what exactly you solved, if this is not classified information. While focusing on how these tasks helped the client’s business + just collect reviews with real names and faces, I think it’s easy to call to ask if the employee is a good employee and a picky client will not be difficult. For foreigners - just a translation of reviews.