Why we built Zennly
A plain calendar can tell you when one person is free. It can't tell you when a provider, a room, and a piece of equipment are all free at the same time—and that's the scheduling problem most service businesses actually have. We built Zennly to model availability as it really works, not as a single grid of open and busy slots.
The problem
Real-world availability is never just one calendar—providers, rooms, and equipment each carry their own constraints, and double-bookings were being resolved by hand, back and forth, one message at a time. Without a timely nudge, booked slots quietly went empty.
Where manual scheduling breaks down:
- • Providers, locations, and equipment each carry constraints a single calendar can't represent
- • Double-bookings get resolved by back-and-forth messages instead of automatically
- • Reminders that go out too early or too late don't stop no-shows
- • Every custom scheduling rule (buffers, combos, specialties) has to be applied by hand
How we built it
We modeled availability as a constraint problem instead of a single calendar: providers, locations, equipment, and custom rules all feed into one engine that computes real openings and resolves conflicts by proposing alternatives or rebooking automatically with approval. On top of that we layered AI-timed, channel-aware reminders tuned to when a given customer is actually likely to respond.
Availability as a constraint problem
Providers, locations, equipment, and custom rules all feed one engine that computes real openings, instead of checking calendars one at a time.
Automatic conflict resolution
When two bookings collide, Zennly proposes alternatives, manages the waitlist, and can rebook automatically once the customer approves—no back-and-forth needed.
Reminders timed to behavior, not a fixed schedule
Reminders go out via SMS, email, or voice at the moment a given customer is actually likely to respond, and make rescheduling as easy as confirming.
Connects to calendars already in use
Zennly syncs with Google Calendar, Outlook, and Apple Calendar, and embeds anywhere through a JavaScript SDK.
What shipped
Automatic conflict resolution with waitlist rebooking
Multi-provider, multi-resource availability modeling
AI-timed reminders built to cut no-shows
Syncs with Google, Outlook & Apple Calendar
Key engineering decisions
Model constraints, not a calendar: Treating availability as a constraint-satisfaction problem is what lets Zennly handle multi-resource bookings a simple calendar can't.
Resolve conflicts, don't just flag them: Surfacing a double-booking isn't enough—Zennly proposes the fix and can apply it with approval.
Reminders should adapt, not just fire on schedule: A reminder timed to when someone actually responds does more than one sent at a fixed hour.
About Zennly
Zennly is multi-branch booking and operations software for spas, salons, gyms and clinics in Nepal, built by Zunkiree Labs. See the product at zennly.io.