Vyte wins in my opinion quite easily over its competitors. It handles all major calendar formats, offers a convenient multilingual interface, and makes it easy to find common slots for several participants.
Last but not least, the price of the deal is attractive, and fortunately includes the Cname. On the other hand, the conditions of access to the API remain mysterious and hypothetical. Vyte obviously hopes to offer it as an optional subscription, which seems unreasonable to me on an LTDs platform. But my main regret comes from the inadequacy of the deal to agencies for their customers, as it is impossible to customize the branding for each user. Too bad, I would have seriously stacked this deal. Anyway, I highly recommend it.