Changelog: Cal.com v6.6 - New Design System and UI Overhaul, New Event Type Settings, Audit Logs & more...

New Design System & UI Overhaul

We've migrated the entire Cal.com application to our new coss.com/ui design system, a modern, accessible component library built on top of Base UI. This release represents one of the largest visual and architectural upgrades in Cal.com's history, touching nearly every core surface of the product.

Besides migrating almost every single component to coss.com/ui we’ve also looked at the user experience of most pages and improved a lot of previously confusing pieces. A long-requested feature for drag and drop was also added during this migration, for event-types, workflows and routing forms.

Event Type Redesign

The event type settings page has been completely redesigned with a live booker preview, giving you a real-time look at how your booking page appears as you configure it. Every setting has been reordered and recategorized for clarity, and we've removed "Advanced settings" entirely as it had become a dumping ground due to a lack of better categories.

Attribute Assignment Audit

We've invested heavily in better clarity to know what is happening inside the platform at any given time. A brand-new audit infrastructure and web UI lets organization admins track how attributes are assigned to members, including changes made via Salesforce and other integration syncs. Admins will now better know what has changed, when, and why.

The past years have always been about the best booking experience with a happy path. We’re investing in a lot of new reporting, auditing and history-reverse tools to make sure the non-happy paths are more visible and easier to address. Scheduling should not be a black box, especially with complex routing logic enabled.

Full coss ui migration

We systematically rebuilt every major surface in the app using coss ui primitives:

• Dashboard: Sidebar navigation

• Bookings: List view, drawer, content list actions, and navigation

• Workflows: List page, empty states, editor, and dialogs

• Event Types: Button menus and search, duplicate dialog, embed dialog, and bulk edit modal

• Routing: Routing and workflow action buttons, routing responses data table

• Data Tables: Team members and org member list

• Shared Components: Phone input and timezone slider

Together, these changes deliver a faster, more consistent, and more accessible experience across the entire application.

Push Notifications in the Companion App

The Cal.com companion mobile app now supports real-time push notifications for your bookings. You'll receive instant alerts whenever a new booking is made, rescheduled, or cancelled, and tapping a notification takes you straight to the booking detail. For booking requests that require confirmation, you can now Confirm or Decline directly from the notification itself without opening the app.

Under the hood, we've built a robust notification infrastructure with persistent device identification, region-aware token management, and identity-scoped delivery. Push registrations are tied to your authenticated session, so switching accounts or logging out cleanly tears down and re-establishes subscriptions with no stale notifications leaking across sessions.

Company Retreat in Japan 🇯🇵

You're probably wondering why it's me, Peer Richelsen, writing the changelog of today.

Well, the entire company is on their annual company retreat, this time in Japan and unfortunately I got sick just days before kick-off so I had to stay home and write this beautiful changelog for you.

Best greetings from the entire Cal.com team, it's been an intense month as usual but from what I can see they are having a blast in the land of Sushi and Wagyu beef.

Oh, and today we are also celebrating 1M verified users and 20M total bookings! 🎉

See you next month.

__

New features

• We've added a right-click context menu to event types and routing forms, so you can quickly duplicate, edit, or manage items without navigating away.

• We've introduced isolated availability for event types, letting you set a completely independent schedule for a specific event type without affecting your global availability.

• You can now reschedule bookings as an organizer while bypassing the host's current availability, making it easier to accommodate special requests.

• We've added routing form history, so you can see a full audit trail of every change made to your routing forms, including route and field reordering, with rich human-readable diffs.

• We've added routing insights API endpoints, giving you analytics on how your routing forms are performing and where bookings are being directed.

• We've introduced a routing trace API endpoint that lets you inspect exactly how a specific booking was routed, step by step.

• We've added SMTP email failover so your booking notifications keep going out even if your primary email provider goes down.

• We've built a domain allowlist backed by the database, giving admins control over which domains are permitted when phishing protection is enabled.

• We've launched personal team trials with a guided onboarding experience, so individual users can try team features before committing to a plan.

• We've added a move-team-to-organization option in org settings, making it simple for admins to bring existing teams under their organization umbrella.

• You can now forward query parameters through the embed snippet generator, so UTM tags and other tracking parameters pass through to your booking pages automatically.

• We've added event type history to the API, so you can programmatically access the full change log of any event type.

• We've introduced per-recipient cancel-seat emails and SMS, so when a seat is cancelled, only the affected attendee gets notified rather than the entire group.

• We've added support for dot-notation relationship fields in Salesforce attribute sync, letting you map deeper CRM fields like Account.Industry directly to Cal.com attributes.

• We've added a CRM owner fallback for routing, so when a lead doesn't have an assigned owner in Salesforce, bookings can fall back to a configurable attribute-based routing rule with options to write back to the account, lead, or contact record.

• We've introduced a booking field render rules engine, giving you fine-grained control over when and how custom booking fields are displayed based on conditions.

• We've added private booking links with configurable usage limits, including an unlimited option for links that should never expire.

• We've launched a payments integration with checkout prefill, platform take rates, and payout portal so you can accept payments for bookings directly.

• We've added Whop integration, letting you gate booking access and render Whop components alongside your event types.

• We've added Attio as a link-based integration, similar to Zapier, so you can connect your CRM without a complex setup.

• We've introduced notification preferences UI, giving users control over which notifications they receive and how.

• We've shipped keyset pagination for insights CSV downloads, so exporting large datasets is faster and more reliable.

• We've added the ability to set and update attribute assignment weights via the API, so you can control round-robin distribution programmatically.

• We've added scheduling-config API endpoints for team event types, making it possible to configure team scheduling rules via the API.

• Salesforce sync errors are now scoped to individual event types, making it much easier to diagnose which event type is having CRM sync issues.

• We've added an integration sync audit log with a full UI, so you can see exactly when syncs ran, what they did, and whether they succeeded.

Fixes & improvements

• We've fixed reschedule emails so they now correctly show the old date and time with a strikethrough, making it clear what changed.

• We've fixed an issue where attendees' locale preferences were lost on reschedule, so booking confirmations now always arrive in the right language.

• We've fixed calendar event ICS attachments to work properly with Outlook and Gmail, resolving issues where events showed "Unable to load event" or failed to auto-add to calendars.

• We've fixed an issue where recurring bookings created duplicate calendar events on confirmation by correctly passing the iCalUID to the event manager.

• We've fixed round-robin host assignment to prevent duplicate hosts when groupId is null.

• We've hardened the booking pipeline to properly enforce rescheduling restrictions, including the disableRescheduling and allowReschedulingPastBookings settings.

• We've fixed timezone handling throughout the booker and calendar components, ensuring date comparisons are always timezone-aware.

• We've added SSRF protection to the ICS feed calendar adapter and OG image handler, preventing server-side request forgery attacks.

• We've fixed HTML escaping in calendar event descriptions to prevent XSS via rich description fields.

• We've fixed the theme flicker that could occur on initial page load.

• We've fixed several scroll and layout issues on mobile, including the booking details drawer, vertical overscroll, drag handle positioning, and event types search.

• We've fixed the Outlook calendar integration to stop false disconnections and properly save credentials even when no default calendar is found.

• We've fixed the lark/feishu calendar OAuth callback that was failing due to a null expiry date.

• We've improved phishing protection to stop flagging password-gated surveys as threats, and added deduplication so the same URL doesn't trigger repeated Slack alerts.

• We've fixed several permission and security issues, including privilege escalation on member invites, credential hijacking via IDOR, and API key hash exposure in responses.

• We've fixed workflow positioning so new workflows and routing forms now appear at the top of the list instead of the bottom.

• We've fixed the booker to scroll to the first missing required field when form submission fails, so users immediately see what they need to fill in.

• We've fixed an issue where the Report Booking dialog would auto-close immediately after opening.

• We've fixed seat responses to be included in the BOOKING_CANCELLED webhook payload for seated events.

• We've fixed phone country detection on cal.eu by checking the cf-ipcountry header, and added a New Zealand custom mask to prevent digit truncation in phone inputs.

• We've fixed CalDAV ICS serialization to use proper CRLF line endings and explicit DTEND instead of DURATION for better cross-client compatibility.

• We've improved the Salesforce integration to correctly change the account owner to the assigned host on round-robin fallback and skip picklist validation for template tokens.

• We've fixed onboarding to show the cal.com URL instead of app.cal.com, and to skip the onboarding redirect for users who are already fully onboarded in SSO flows.

• We've migrated OAuth JWT signing to keyring encryption for improved security.

• We've fixed the embed dialog grid layout and success page embed UI.

• We've improved performance by replacing the Postgres calendar cache with a unified KV-backed service and adding caching with single-flight deduplication for Cal Video sessions.