Open-source development is an unconventional contract where firms can attract volunteer developers as inexpensive labor. Using firm-task-developer level panel data, I show that firms attract more open-source labor when facing an adverse venture capital shock, which generates spillovers that weaken the volunteer labor market. The collapse of a crypto startup in 2022 reduced availability of VC funding for other startups. Treated firms hired 6.1% fewer employees and relied on 10.5% more contributions from non-employees. Marginal contributors were of lower quality and future employers were 9.7% less likely, relative to the unconditional mean, to hire volunteers contributing to treated startups.