It is not possible to Tip anonymously on Tipeee.
Some personal information is indeed required to issue the invoice for your support, but also to allow the Creator to manage the Tips received and any rewards offered.
At minimum, the Creator you support has access to your first name, last name and e-mail address.
In some cases, additional information may also be requested when you make your Tip, such as your postal address or phone number. This is particularly the case when a physical reward needs to be sent to you.