There are two rounds of interviews.
The first round is a technical phone-screen interview, which is 45 minutes long.
The second round is a virtual onsite interview, consisting of four technical rounds.
I heard back two weeks after the final interview.
Mostly LeetCode-style algorithms/data structures questions.
There is one "pair-programming" round where you have to implement some functionalities in an industry-like environment.
The following metrics were computed from 3 interview experiences for the Duolingo Software Engineer - New Grad role in United States.
Duolingo's interview process for their Software Engineer - New Grad roles in the United States is extremely selective, failing the vast majority of engineers.
Candidates reported having very good feelings for Duolingo's Software Engineer - New Grad interview process in United States.