Way better alternative to Calendly and Google's built-in availability/meeting booking service because its free plan lets you connect to different calendar accounts. It also has the nicest design among its competitors
Kinda big learning curve but worth it imo. You can link notes together and basically create your own personal Wikipedia/digital brain. I also use this as my journal. And all the notes are future-proof cause they're stored as plain text files. There's a very large extensions/plugins community too