They rescind the oral offer without any explanation. Got through two rounds of phone interviews and a third one was scheduled. On the appointment day, I waited for half an hour but no one called me. Then the recruiter approached me saying they would like to extend me an offer. Well, that's surprising but still great. We talked about the offer and I tried to negotiate a little bit. A couple days later, they called back and told me nothing in the offer can be improved. So I ask the HR if they are comfortable with giving me a couple more days to consider. The lady kindly promised me to check with the hiring manager. Next day, after emailing them an acceptance, I received the feedback that they had decided to withdraw the offer. None of the recruiting staff replies to my email since then. The process made me feel VERY uncomfortable. It's okay if something has changed on their end, but I expected their response in a more respectful way.