The Many Brains Project is a 501(c)3 non-profit that promotes the values, techniques, and tools of open, participant-centered brain science. The Many Brains Project (1) provides access to high quality cognitive tests and (2) supports the development of infrastructure, software, and research initiatives that emphasize open science solutions, participant-centered research, and help further the science of the mind / brain and brain health. At Many Brains, we believe brain science will benefit most from an approach that involves the active collaboration of many participants, many researchers, many organizations, and many communities. We have a vision of a brain science that emerges from the contributions of many brains, built on a foundation of openness, accessibility, and integrity. Many Brains operates the popular cognitive testing platform, TestMyBrain.org, where we have tested 2.5 million people.