For many studies it's useful to be able to sort users into multiple groups. For example, you may want to send 50% of people to one set of instructions, and 50% to a second set of instructions. Or you may want to give 90% of people one form to fill out, and a test group of 10% of people a different form. It's important people are randomly assigned to groups.
Using this tool you can create a single link which will redirect people to up to 10 different possible URLs.
If the same user clicks the link a second time in the same browser, they will be redirected to the same destination.
If all links have the same weight, they will redirect equally. If you give link A a higher weight, for example 9, and link B a lower weight, for example 1, then 90% of users would be directed to link A and 10% to link B.