The present perfect, 'Who has viewed my profile?' would be more natural here, as the implicit timescale is 'so far' or 'up to now'. The profile is still available for people to see.

'Who viewed my profile?' would set the context at a fixed point in the past, for example if the profile had been been taken down and it was no longer possible to view it.

You're welcome!

I can also picture: "<em>who is viewing my profile? " </em><em></em>where the emphasis is placed on who rather than on the time aspect.

@Su.Ki.

Thank you very much for helping!

I am at my work now and I even had a discussion with colleagues with  about it.

Nobody knew the correct answer.