More than 100,000 people have had their eyes scanned in return for a cryptocurrency called Worldcoin, as a project to distribute digital money more widely around the world accelerates.

Worldcoin has distributed about 30 iris-scanning hardware devices, which they call “orbs,” to early users on four continents, who get rewards for signing up more people. Orbs take photos of a user’s eyeballs, creating a unique code that can be used to claim free digital tokens.

The project’s developers said on Thursday they planned to release hundreds of orbs in the coming months and eventually distribute 4,000 devices per month. The team plans to debut the cryptocurrency network early next year and begin giving away the tokens at that time. They have not said how much cryptocurrency users can expect to receive.