Reached by recruiter of OneSignal. Overall process was quick, from intro call all the way to onsite took like 3 weeks. Instead of actually testing how good you are at coding, they tend to talk about your experience and getting to know your project during the phone interview round. I think it is better than doing algorithm question in phone interview round, because they are looking to know who you are and what have you been through during your past experience. If you really did what you said in the resume you should do well in the phone interview round. During the onsite interview, you get to meet with many experienced engineers and leaders of the company. Instead of being super good at leetcode questions, you should gain more understanding of the language you said you have experienced with. Their interview style is totally different with big flag companies such as, F , G , A etc. Problem solving is important, but being a good team player is also key factor here. The overall onsite interview experience is like a friendly pair-programing process. You don't need to be perfect, but reveal how you think and approach. If you love collaborative team work, family team culture, grow with team, and wear multiple hat, definitely try to apply and show who you are.