Quick answer. Virto Calendar App has no event permissions of its own. It shows events from your Microsoft 365 sources, such as Outlook calendars, SharePoint lists and group calendars, and each person sees and edits only what their own Microsoft 365 rights allow in each source. Virto Shared Calendar works the other way: it keeps its own events, and the calendar’s owner decides who views and who edits. In Virto Calendar App everyone who opens the calendar needs a licence; in Virto Shared Calendar only the people who add or edit events do.
Sales teams hear the same three questions about Virto calendars: who will see this calendar, who can change it, and why does my colleague see something I do not. This guide answers them for both products, source by source.
Two products, two permission models
| Virto Calendar App | Virto Shared Calendar | |
|---|---|---|
| Where events live | In your Microsoft 365 sources: Outlook and Exchange calendars, Microsoft 365 group calendars, room and equipment calendars, SharePoint lists, Planner, public folders, iCal feeds | In the calendar itself, stored by VirtoSoftware on Microsoft Azure |
| Who decides who sees an event | The source: each person sees what Microsoft 365 lets them see | The calendar’s owner: private, organisation-wide or shared by link |
| Who can add and edit events | People with edit rights in the source | Owners and members of the calendar |
| People outside your organisation | Only as guests of the SharePoint site that holds the calendar | A share link with view or edit access, no Microsoft account needed |
| Who needs a licence | Everyone who opens the calendar, people who only view it included | Only the people who add or edit events |
Virto Calendar App: the source decides
One consent, then each person’s own rights
A tenant administrator installs the app and grants consent once for the whole organisation. After that, the app reads and writes events through Microsoft Graph with delegated permissions: every request runs with the rights of the person who is signed in. The app does not use application permissions that would let it see more than that person can.
Who sees what
A calendar in Virto Calendar App is a set of sources shown together. When a person opens it, each source is loaded with that person’s rights:
- A source they can open in Microsoft 365 shows its events.
- A source they cannot open simply does not appear for them. The rest of the calendar works as usual, with no error.
So two colleagues who open the same calendar, on the same SharePoint page or in the same Teams tab, can see different events. That is expected: the calendar never shows anyone an event that Microsoft 365 would hide from them.
Adding the calendar to a page or a Teams channel does not change this. Hiding a web part from an audience on a SharePoint page controls who sees the web part; it does not grant or remove access to any event.
Who can add and edit events
Edit rights come from the source as well:
| Source | Who can add or change events |
|---|---|
| SharePoint list | People with the Add Items, Edit Items or Delete Items permission on the list. View Items alone means view only. You can also set a SharePoint data source to read-only in the calendar. |
| Outlook or Exchange calendar | People the owner gave edit or delegate access to in Outlook. Read-only access stays read-only in Virto Calendar App. |
| Microsoft 365 group calendar | By default, every owner and member of the group. See below for how to make it read-only in the calendar. |
| Public folder | People with Editor, Publishing Editor or Owner rights on the folder. Reviewers can only view. |
| iCal feed | Nobody: iCal feeds are read-only. |
In the Multi Source view you can edit and resize events, but you cannot move an event from one source to another.
Microsoft 365 group calendars and how they overlay
Each Microsoft 365 group has its own calendar, and Virto Calendar App can show several of them in one view:
- In Outlook on the web, open Groups, select the group and copy its email address.
- In the Virto calendar’s settings, open Exchange settings, choose Display events from resource calendars and paste the address.
- Repeat for each group, then give each group its own background and font colour, and turn on the legend in the General settings so people can tell the groups apart.
Two rules decide what people see in such an overlay:
- Only members see a group’s events. Microsoft 365 opens a group calendar only to the members of that group, so a colleague who is not a member will not see that group’s events in the overlay. Guests cannot open group calendars at all (Microsoft Learn). If everyone should see every department’s events, either add people to the groups or keep those events in a source everyone can read.
- Members can edit unless you say otherwise. By default all owners and members of a group are editors. To keep a group calendar read-only in the overlay, click the gear next to that group calendar and set its members to Reviewer. This applies inside Virto Calendar App; to change the rights in Exchange itself, an administrator uses Exchange PowerShell.
When most people only need to view a calendar and a few people keep it up to date, a SharePoint list is often the simplest source: give everyone View Items and the editors Add Items and Edit Items.
Who can change the calendar itself
Events are one thing; the calendar’s settings are another. Under the gear icon, Settings > Permission names who may change them, for the whole tenant or for the current site:
- Calendar Managers edit calendars and their data sources.
- License Managers manage licences and assign Calendar Managers.
- Site collection administrators are always on the list.
Everyone else uses the calendars without changing them: people with read-only access cannot save, copy or delete calendars or data sources.
People outside your organisation
Virto Calendar App has no public or anonymous link. External people take part as guests of the SharePoint site that holds the calendar: they see, and edit if the site allows it, the Virto calendars on a site they can open. They cannot open Microsoft 365 group calendars or their own personal calendars there, and external users in Teams shared channels are not supported.
Virto Shared Calendar: the calendar decides
Virto Shared Calendar is a separate web and Teams app. It does not read your Outlook or SharePoint calendars; it keeps its own events, which VirtoSoftware stores on Microsoft Azure. Its permissions are set on each calendar under Calendar settings > Permissions:
- Private calendar. Ticked, only you can see the calendar. Unticked, all users in your organisation can see it.
- Permission mode. In Default mode, every user opens the calendar as an owner. In Restricted mode, owners edit events and change the calendar, members edit events, and everyone else only views.
- Owners and members are added by name or email.
Sharing outside the organisation is built in. A share link gives view-only or edit access to anyone, with no Microsoft account needed, and another Microsoft 365 tenant can add the calendar by pasting its link under Add shared calendar. You can also add iCal feeds, such as public holidays, to the view.
One thing to check before you add external people to Microsoft Teams: an external user you add to your team can also see your Virto Shared Calendar.
Licences follow the same split
- Virto Calendar App: everyone who opens the calendar uses a licence, including people who only view it. A licence is assigned automatically the first time a person opens the app, and one licence covers that person in SharePoint, in Teams and in the browser. Count the people who will actually open the calendar, not everyone in your tenant.
- Virto Shared Calendar: only the people who add or edit events need a licence. Viewers are free.
Which one fits
- Choose Virto Calendar App when your events already live in Microsoft 365, in Outlook, group calendars, SharePoint lists or Planner, and you want one view of them that respects every source’s permissions.
- Choose Virto Shared Calendar when you need a standalone calendar that many people view and a few people edit, or that you share with people outside your organisation by link.
Not sure? The comparison of the two calendars puts them side by side.
