The Giving Pledge was launched in 2010 by Buffett and the Gateses after having “conversations with philanthropists around the world about how they could collectively set a new standard of generosity among the ultrawealthy,” according to the Pledge’s website. Donors have given to a range of causes, including refugee aid, disaster relief, education, women’s empowerment, medical research and environmental sustainability. The Pledge’s public face is intended to draw more people into philanthropy and get signatories to be more charitable earlier in life.

This year’s 19 Pledge donors include WhatsApp co-founder Brian Acton and Brian Armstrong, CEO and co-founder of the cryptocurrency company Coinbase. The list now includes 204 donors from 23 countries committed to giving away half of their wealth to charity during their lifetimes or in their wills.