Doodle is a well-known tool to plan your meetings, but it is financed via tracking and ads. That’s also why they lock out adblock users.
Framadate is an easy-to-use libre Doodle-style event and poll service, provided by France’s largest ethical software organisation Framasoft. It costs nothing, it doesn’t track you and you don’t need to register.
Also, it can be selfhosted. That’s why it’s also hosted on multiple domains. If you enjoy using the service you can donate to Framasoft or to the other hosting providers to keep them going, but that’s entirely optional.