Onboarding is probably one of the hardest parts of the job. Keeping code quality high and documentation definitely help. One thing I don’t see mentioned in the thread yet is mentorship. I try to spend more time with new hires to help them build a plan for contributing and identify gaps in their knowledge and how to fill them. I also look for opportunities for them to work closely with more experienced devs on the team. Besides having another person to learn from to who isn’t their manager, I find the experienced devs appreciate the chance to share what they know.