Side by side
Duet vs WhenTo
Both stand on calendar apps. Which one you can start free with, which one lets you read the code, and what each costs once you pay.
Free plan iPhoneMac
Visit Duet Free plan Self-hostedWeb
WhenTo focuses on recurring scheduling around shared availability rather than one-off polls. Its free cloud option is capped at three calendars, while self-hosting removes that calendar limit but requires operating the software yourself.
Visit WhenToThe facts
| Duet | WhenTo | |
|---|---|---|
| Free plan | Yes | Yes |
| Open source | Not published | Not published |
| Runs on | iPhone, Mac | Self-hosted, Web |
| Lowest paid plan | Yearly Subscription: $19.99 a year | Free or on request |
| Plans published | 5 | 2 |
| Maker | Not published | Not published |
| Website | duetcalendar.com | whento.be |
| On calendar apps | #83 of 194 | #87 of 194 |
Duet: what it does well
WhenTo: what it does well
- Weekly availability patterns and exceptions
- Threshold notifications through four channels
- Shared-link participation without accounts
- Unlimited calendars when self-hosted
- Docker Compose deployment instructions
What to know first
- Cloud accounts are limited to three calendars
- No paid tier to raise the cloud limit
- Calendar synchronization is one-way
- No mobile apps listed