Many different rounds.
Interviewed by 5 people for 45 minutes each.
Interviewed based on role-specific fit and company-related fit.
The interview process is well-documented on many different websites.
I recommend you practice coding beforehand.
Many rounds of skills testing, then cultural fit questions.
The following metrics were computed from 3,728 interview experiences for the Google Software Engineer role in United States.
Google's interview process for their Software Engineer roles in the United States is extremely selective, failing the vast majority of engineers.
Candidates reported having very good feelings for Google's Software Engineer interview process in United States.