OpenSlot vs Calendly
Booking pages versus paste-ready availability lists: an honest comparison of Calendly and OpenSlot for people who schedule over email.
The short answer
Choose Calendly
Choose Calendly when strangers book you at volume and you want automation around each booking (reminders, forms, payments).
Choose OpenSlot
Choose OpenSlot when scheduling happens inside email threads, when you're offering times to clients or executives, or when you need one merged list for several Outlook calendars.
On this page
Calendly popularized the booking link: a page where other people pick a slot on your calendar. OpenSlot takes the opposite approach — it hands YOU the list of free times as text, and you paste it into the conversation you're already having. Which one fits depends mostly on who you're scheduling with, and who should carry the etiquette burden.
A comparison page is not worth reading if it cannot say what the other tool is genuinely better at, so both sides get stated plainly.
Where Calendly shines
- Inbound scheduling at volume — sales demos, recruiting screens, office hours — where dozens of strangers book themselves onto your calendar.
- Automated reminders, routing forms, payments, and round-robin distribution across a team.
- A polished ecosystem of integrations far beyond Microsoft 365.
Where OpenSlot takes a different approach
- No booking page and no link etiquette: sending clients or senior people a "pick a slot on my page" link can read as making them do the work. A pasted list reads as an offer, not homework.
- Group availability: OpenSlot merges several colleagues' Outlook calendars into one list — Calendly's strength is one person's (or one team's) bookable time.
- Lives inside Outlook: build and insert the list without leaving the email you're writing.
- The other person needs nothing: no page to visit, no account, no cookie banner — they just reply to your email.
Side by side
| Dimension | Calendly | OpenSlot |
|---|---|---|
| Core object | A booking page others visit | A paste-ready text list you send |
| Who does the work | The invitee picks from your page | You offer times; they just reply |
| Group scheduling | Team event types | Merges any colleagues' Outlook free/busy |
| Where it lives | Web app + integrations | Web app + Outlook compose pane |
| Calendar sources | Google, Microsoft 365, others | Microsoft 365 (Outlook) |
| Recipient needs | Visits your page | Nothing — plain text in the email |
Common questions
Can I use OpenSlot and Calendly together?
Yes. Many people keep a booking page for inbound requests from strangers and use OpenSlot when they are the one offering times inside an email thread, for example to a client, a candidate or an executive. The two do not conflict: OpenSlot only reads free/busy, so bookings made through Calendly simply show up as busy time.
Does OpenSlot work with Google Calendar?
No. OpenSlot reads Microsoft 365 (Exchange Online) calendars only. If your team is on Google Workspace, a booking tool or Google Calendar's own appointment schedules will fit better.
Does the person I'm scheduling with need an account?
No. They receive plain text in your email, with the times already in their time zone if you chose it, and they reply with the slot that suits them. There is no page to open and nothing to sign up for.
What does OpenSlot see in my calendar?
Whether each block of time is free, busy, tentative or out of office, which is all it uses. For calendars you can already see in detail, Microsoft includes meeting subjects and locations in the same response; OpenSlot discards them, never asks for attendees or notes, and does not store calendar data. Availability is computed when you ask for it.
OpenSlot
Try the list approach
Every new OpenSlot account starts with 14 days of Pro — no card, and nothing for the person you are scheduling with to install, visit or sign up for.
Try OpenSlot freeSign in with Microsoft, pick people, paste the times.