Gustaf Alstromer is a Group Partner at Y Combinator, where he has worked with over 600 startups and reviewed more than 9,000 applications. He focuses on growth strategies and climate tech investing, having co-invested in over 130 climate companies.

Gustaf co-founded Heysan, a mobile messaging app in the YC Winter 2007 batch, which was acquired by Good Technology in 2009. He grew up in Sweden and studied at Hyper Island before moving to the United States.

Gustaf helped start and lead the Growth team at Airbnb from 2012 to 2017, building it from a few people to over 100. He previously served as Head of Growth at Voxer, a walkie-talkie app for smartphones.

The YC companies Gustaf has worked with are worth a combined $118 billion. He has been a Group Partner at Y Combinator since 2017, after serving as a Visiting Partner in 2016.

Gustaf co-authored Y Combinator's Request for Startups in climate tech and has invested in over 130 climate companies. He is recognized as an expert in product-market fit, user growth, and applying data-driven methods to startup scaling.