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Hourmere Cloud is in an invitation-only preview with sign-ups closed, and the open-source release for self-hosting is planned for November 30, 2026. Its self-hosting guide requires a source build; no prebuilt public image is published. This page describes the documented implementation and its current limitations.
The verification date above applies to the linked sources on this page. Follow them for current availability, terms and plan requirements before choosing a service.
Deployment and ownership
Section titled “Deployment and ownership”| Option | Deployment | Source and operating responsibility |
|---|---|---|
| Hourmere | Build from source with Docker Compose: application and PostgreSQL; workers can run separately. See self-hosting. | You operate the instance, backups, email delivery and calendar credentials; see the configuration reference and backup guide. |
| Calendly | Vendor-hosted scheduling and MCP service. See its service terms and MCP documentation. | Its MCP documentation explicitly excludes self-hosting or local deployment of that server. |
| Cal.com | Managed service or commercial enterprise self-hosting, as described in its self-hosting guide. | Cal.com’s transition announcement describes a private production codebase. Its self-hosting guide directs enterprise deployments through its team. |
| Cal.diy | Community edition installed on your infrastructure; see its README. | MIT-licensed. Its self-hosting documentation recommends personal, non-production use and describes the operator’s responsibilities. |
Cal.com and Cal.diy are different offerings. Cal.com’s technical transition announcement describes the private production codebase and MIT community edition. Its self-hosting guide explains commercial enterprise self-hosting. The Cal.diy self-hosting documentation describes its installation model and operating warning.
For Hourmere’s actual setup and maintenance requirements, read the self-hosting guide, configuration reference and security policy.
Access for agents
Section titled “Access for agents”Hourmere accepts an organization-bound API key for REST and MCP. Once a verified user has created a key, a script or agent can discover configuration, find slots and manage bookings without a browser authorization flow. Creating an account and obtaining a key are still setup steps; possession of a key grants the permissions described in the REST quickstart and MCP quickstart.
Hourmere’s MCP OAuth guide also describes opt-in browser authorization, explicit organization approval and revocation through Connected apps. The instance needs HTTPS outside loopback development; verify the intended hosted client separately before relying on it. See the MCP protocol documentation for the current implementation and limits.
Calendly also has both a REST API and MCP support. Its REST API introduction documents personal access tokens and OAuth. Its MCP authentication documentation requires OAuth Authorization Code with PKCE and dynamic client registration; personal access tokens are not accepted by that MCP server. This is a transport-specific difference, not a claim that Calendly has no API access for scripts.
Cal.com’s transition announcement says Cal.diy retains API v2 alongside its booking engine. Check the particular edition’s API and authentication documentation for your integration; an API in one offering does not establish compatible MCP support in another.
Check the features you need
Section titled “Check the features you need”Hourmere documents personal booking and availability, booking creation, rescheduling and cancellation, opt-in inline and popup widgets, and Google Calendar connections, busy-time synchronization and booking event writes.
Check the documented limits when evaluating it:
- Microsoft calendar connections list calendars and refresh credentials, but do not synchronize busy times or write booking events.
- Zoom account connections are separate from sign-in and calendar connections. Identity-only authorization does not create or read meetings.
Cal.com’s transition announcement and Cal.diy documentation distinguish the community edition from commercial Cal.com: Cal.diy excludes teams, organizations, workflows, SSO and the Insights dashboard. This does not exclude the analytics integrations listed in the Cal.diy documentation. Check the edition’s feature list rather than assuming identical features.
For any option, try the complete workflow with your intended client and provider: discover availability, book, retry a request, reschedule, cancel, and check the resulting calendar and email. Confirm permissions, recovery and data-retention needs against that product’s documentation.
Product names and independence
Section titled “Product names and independence”Calendly is a trademark of Calendly, LLC; see its legal definitions and intellectual property terms. Cal.com is a trademark of Cal.com, Inc.; see its trademark notice. Cal.diy is a trademark of Cal.com, Inc.; see the Cal.diy trademark notice. Other product names identify their respective products; any associated trademarks belong to their respective owners.
Hourmere is not affiliated with or endorsed by Calendly, Cal.com or the Cal.diy project.
Calendly and Cal.com are trademarks of their respective owners; Hourmere is not affiliated with or endorsed by them.