As stated in the title, I’m looking for an online appointment scheduler that basically lets clients see available appointment times via a calendar and then book themselves in for a chosen time/date. Any API’s or third party plugins that are recommended? All the better if they are compatible with Infusionsoft customer lists.
I recommend AppointmentCore. It has a direct integration with Infusionsoft and your Google/Exchange calendar.
Schedule Once is what we recommend and use for all our clients. The integration is seamless.