This tool is donation-supported. That means that we do not track users with commercial purposes, sell advertisements or offer any paid services. However, we rely on your donations to fund software development, the purchase of books and software, and cover infrastructure costs.

You can make a donation of any amount of your choice. If you're looking to make a different kind of contribution, please consider organizations such as MSF, Save the Children, the ACLU, Planned Parenthood, or the EFF. Thank you!