I'm another one of the engineers at thredUP. I've been with the company for 5 years and I can vouch for Ryan when he says there's a big focus on professional development. We've had engineers who started on our web team, moved to the operations team 2 years later because of an interest to learn RabbitMQ, which the operations team was using for a project, and now works on the mobile team. Happy to answer any questions about the team as well (dan at thredup.com).