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.
CryptPad is a collection of open source and privacy-friendly collaboration tools. They let you easily create documents, presentations, sheets, polls and more in your browser. Based on the “zero knowledge” concept, no one except you (and whoever you give your access keys to) can access your data.
The service is free up to a certain storage limit, with paid accounts for additional storage. You can even use the free service without registering if you want to. It’s worth registering though, as you can keep your documents permanently online this way.
If you are using Nextcloud, the Polls extension is a good option for creating Doodle-style events and polls. You can make it public or limit access to certain users on your Nextcloud instance.