After more than a month of waiting, I received an offer from a potential employer last week. However, the day before they contacted me about the offer, another company set me up for an interview. Currently, I'm the process of negotiating the contract with the first company, and I'm not really sure if I should tell them about the the other company (and not really as a form of leverage). I want the entire process to be transparent (as much as possible) for all parties involved but I learned in the past few months that job application is a weird process where telling the truth may get you in trouble.
Would it be weird to tell the employer with an offer to wait while I go through the process with the other company? Should I tell the other company that I already have an offer from the first one? I'm not very far in process with the new company (step 2/4 or 2/5 I think), so I may not even get an offer from them. I'm afraid that if I don't do the right thing now, I might end up with zero offers in the end.