Delegate your day.
Calendar app for Gmail and Outlook
Otto puts a Google Calendar or Outlook calendar next to your mail. Its assistant proposes meetings from the thread and asks before it books.
You just approve.
The short version
- Your events stay in Google Calendar or Outlook. These apps show and edit them, and nothing is copied into a new calendar.
- Otto is mail plus calendar plus tasks. Spark is a mail client with a calendar. Fantastical and Notion Calendar are calendar-first apps, and so is Morgen.
- Otto Free includes the calendar on one connected account.
- Last reviewed 2 November 2026. Plans change, so check each page before paying.
The short answer
If you want your calendar in the same app as your mail, Otto shows your Google Calendar or Outlook calendar beside the inbox. Its assistant proposes a meeting from a thread and books it once you approve. If you'd rather have a calendar-first app, Fantastical connects Google and Outlook calendars, and so do Notion Calendar and Morgen. Your events stay with Google or Microsoft either way.
At a glance
| App | Calendars it connects | Built around | Suits |
|---|---|---|---|
| Otto | Google Calendar and Outlook | Mail, calendar, tasks | Booking from the thread, with approval |
| Spark | Multi-provider support | Mail client | A calendar inside a free multi-account client |
| Fantastical | Google, Microsoft 365, Exchange, iCloud, CalDAV | Calendar and tasks | A calendar-first app on Apple and Windows |
| Notion Calendar | Google Calendar, Outlook, iCloud | Calendar | A calendar with a free option |
| Morgen | Google, Outlook, Apple, Fastmail | Planning calendar | Planning with tasks from other tools |
What Otto's calendar does
- Day and week views, a month view and an agenda, and G then C opens the calendar.
- You can create events by hand, and drag them or resize them, without leaving the inbox.
- To book from a thread, ask Otto to find a slot with someone. It reads the thread, and it'll propose proposes the event with attendees and time zone showing, and books it after you approve the card.
- Attach a Google Meet link, or a Teams link where an Outlook event is set up for one.
- Select events in Agenda to delete them together, or ask Otto to review them. Each AI confirmation covers up to 200 events, guest notifications follow the provider's rules and deletion can't be undone.
- Promote a task to a calendar event when it needs a time.
The selected account decides which calendar you're in, so a work event can't land on a personal calendar by mistake. Free connects one account. Gmail and Outlook together come with a paid tier.
What to check before you choose
Start with which calendars the app reads. Fantastical also connects iCloud, and so do Notion Calendar and Morgen, while Otto uses the calendar of a connected Gmail or Outlook account.
Then where it runs. Otto is on the web and on iPhone, and there's no native Mac or Windows app. Fantastical's page lists Apple and Windows apps, and Notion Calendar's page lists desktop and mobile apps.
A calendar-first app leaves mail to another app, so ask yourself whether you'll need the mail too. Otto and Spark include both.
And ask what the assistant does when it isn't asked. Otto shows a card before it books anything, and before it sends or changes anything.
What it costs
Free covers one connected account with core mail, calendar and tasks, plus an AI allowance. Paid tiers add more accounts and capacity, plus extra features. Where a vendor's price is in our table, it comes from its own pricing page, which we read in October or November 2026. Fantastical and Notion Calendar list plans on their own pages, so we give none.
| Product | Lowest paid plan | Price | Notes |
|---|---|---|---|
| Otto | Plus | from $6.99/month | Pro $19.99/month; $55.99/year for Plus |
| Spark | Plus | from $10/month | per seat, $8.25/month billed yearly |
| Morgen | Individual | from $30/month | a planning calendar, not a mail app, $15/month billed yearly |
Where Otto fits, and where it doesn't
Otto fits if your meetings start in email. The thread, the proposed time and the invite sit side by side, and you're the one who approves the booking.
It doesn't fit if you want a calendar-only app or a native desktop app, or iCloud or CalDAV calendars. And don't expect it to join or record meetings, because it doesn't.
Read more
- One app for email with calendar and tasks
- The roundup of calendar apps and schedule meetings from email
- Otto vs Fantastical and Otto vs Notion Calendar
- Otto vs Morgen, Otto vs Motion and Otto vs Akiflow
- Plans are on the pricing page
How we checked this
Last reviewed 2 November 2026. Sources: Spark's pricing page, Fantastical's page, Notion's Calendar page and Morgen's home page. Otto is ours, so weigh what we say about it with that in mind. Nobody paid for a place here.
Questions, answered
What is a good calendar app for Google Calendar and Outlook?
Otto connects both, and so do Fantastical, Notion Calendar and Morgen. Otto adds mail and an assistant that books after you approve. The calendar-first apps leave mail to another app. Your events stay in Google or Microsoft either way.
Does Otto copy my events into its own calendar?
No. Otto shows and edits the calendar of the Google or Outlook account you connect. Your events stay with your provider.
Can I use Otto's calendar without the AI?
Yes. Create events by hand, and drag them or resize them. The calendar's on Free, and the assistant is there when you want it.
Try your next step in Otto
Core mail, calendar and tasks are free. AI has an allowance.
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