Refactor is a seed-stage venture firm led by Zal Bilimoria and based in Burlingame, California. It backs US-based hard-tech startups that build physical systems across aerospace, energy, bio, critical materials, immune health, and AI infrastructure, prioritizing durable moats, long development cycles, and sticky customer value. The firm makes first-dollar checks to founders rebuilding industries and operates with a founder-first approach. Its portfolio includes Solugen, Astranis, PathAI, Clover Health, Knowde, Berkeley Yeast, 64-X Bio, Phytoform, Onyx Bio, Headspace, and other ventures. Refactor has notable exits and scale, including Uniform Teeth's acquisition by Impress, Kip's acquisition by Modern Health, and Clover Health's public listing. Zal Bilimoria joined a16z in 2013, helped launch their Bio Fund, and founded Refactor in 2015 as an early spinout. The firm is based in Burlingame and invites ambitious teams to submit opportunities for consideration.