What is Omnipointment?
Omnipointment offers cooperative scheduling to find the best time for a group to meet. Key Features
Time Grids: Visually present dates/times. Times display in user's local time zone to avoid confusion. Calendar Agnostic: Time grids let users without detailed calendars easily mark free time. Calendar users can import availability! One Touch RSVP: Availability is saved with a user, not just the meeting. When responding to other meeting requests in the same time range, your schedule will copyover automatically. Filtering: Easily see schedules of specific people or groups in your time grid so you can prioritize their attendance. Finalize Time: When a time is picked, users' availability updates automatically to prevent double bookings with other organizers.
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Comments and Reviews
Said about Omnipointment as an alternative
It has near identical functionality, allowing people to "paint" when they are available and aggregating that data. WhenIsGood has some more functionality, especially in the premium version and if you create an account, but this definitely works.
Similar functionality. Dead simple, no registration needed. Note that unlike WhenIsGood, it allows your respondents to see everyone else's answers, which you may or may not want.