Admissions - University - Graduate School. Is this a commitment? I recently applied to a graduate engineering program at a university and was contacted by a professor who was interested in my application. We discussed the projects that he is undertaking and seems to think I would be a good addition to the team. A week after the interview, he reached out stating that he has instructed the university to offer me the MASc position in the program I was applying for, and discussed the courses he would be interested in having me taking and the total funding he is willing to provide for the program. I replied back stating that I would love to join his team.

My concern so far is that I have not received an official letter of admission from the university and I am not sure if it is practical or ethical to apply to other universities in the meantime in order to ensure that if things won't work out I have a backup plan.

My question: is this the right thing to do or should I wait for the decision to arrive from the main university I applied to?
Not knowing the policies of the university and whether the offer from the professor amounts to a commitment or not, I'd say yes, you can apply elsewhere, but as you have given at least a verbal/email/whatever assurance, you can't accept any other offer. 

I would make other inquiries somewhat discrete, however, so as not to cause concern should the first professor learn of them. You also shouldn't represent yourself as being entirely free to accept an offer in the interim. 

But you can also inquire of the administration of the first university what is the actual meaning of the offer given and accepted. Can you expect paperwork to follow or is it still tentative? You have a right to know this, of course. 

You could also, perhaps, ask this question of the professor involved, asking him/her whether you should keep looking or is it a signed-sealed-delivered offer. 

You don't need to leave yourself at risk, but you shouldn't put others at risk either. 

And congratulations.