Prolific

Researchers set screening criteria, such as age, country, or language, and pay participants for their time. Participants are vetted, and the platform tracks quality. It connects with survey tools like Qualtrics and experiment builders.

Pricing is based on participant payments plus a platform fee. Samples are online volunteers, so results may not represent the general population.

MTurk and CloudResearch are alternatives. Prolific suits behavioral scientists and academic researchers.