I've applied from facebook.com/careers and 3 weeks later a recruiter sent an email that they were interested in to make an interview. They were very kind and interested. I got a detailed instruction about the process. Also they gave me some blog posts or other links that I've already found at my company research. They said that the phone interview worth to prepare and I may take time to study. I wanted 2 weeks to get ready and they accepted that. Than, someone else (another recruiter) got in touch to create the schedule of phone interview. After creating appointment, before that 2 weeks, they called me to just talk. It took about 5 mins. I asked some questions about the company and recruitment process. After two weeks I got a call and that was an engineer. He asked me some questions about my background. After answers, I've signed in to an online editor to write some code in shared session. They asked two algorithm questions and I thought I was not so bad. After these questions, he asked to me that do I have any question about company or technology. I've asked something to just ask. He answered them very kindly and detailed. After 45 mins at talk, he said that's time to go. About 5 hours later, I got an email from the first recruiter that I'm not suitable. Also the recruiter has added as a contact on linkedin. That was completely sign of they are nice and they want über people.

1 code signal online assessment into 2 interviews with 2 leet code medium style questions around a 40 minute time frame as well as 1 behavioural interview with SWEs to gauge culture fit.