If you want a group calendar that works with AI, the difference is who built the connector. Junto ships an official, built-in one that uses a revocable key. For Cozi and TimeTree, only unofficial community MCP servers exist, and they sign in with your account password. Teamup has a third-party connector from viaSocket.
Junto wrote this page, so read it as a vendor comparison and check the sources. Facts were checked on 2026-11-06. Google Calendar is left out because we could not verify its assistant support on a primary page.
See how the built-in connector works and add it to Claude or ChatGPT.
We looked at five things that matter when an assistant touches a calendar you share with other people. Criteria first, so you can judge the result.
The short version: only one of these four has an official connector from the calendar maker. The table states what each project's own page says.
Group calendars and their AI assistant connectors
| Criterion | Junto | Cozi | TimeTree | Teamup |
|---|---|---|---|---|
| Connector made by | Junto itself (official, built in) | A community project, "unofficial" | A community project, "not affiliated with TimeTree" | viaSocket, a third party |
| How it signs in | A personal key in the link, stored as a hash, revocable | Your Cozi username and password | Your TimeTree email and password | Not described on its page ("built-in authentication") |
| Where it runs | Hosted: paste a URL into Claude, ChatGPT or Claude Code | Installed and run by you with your credentials | Runs locally on your computer over stdio | Hosted by viaSocket |
| What it can do | List events, see who is going and who has not answered, add events, RSVP as you, create a calendar | Lists and calendar, including creating, changing and deleting | Search and change events, memos and comments, including delete | Five actions listed, including create and get bookings |
| Can it delete? | No | Yes, by default | Yes | Not listed |
| What other members need | A link and a name | Per Cozi: an account | Per TimeTree: an account and an app for full use | Per Teamup: access by link, no RSVP system |
Checked 2026-11-06 on each connector's own page: github.com/mjucius/cozi_mcp, github.com/ap311036/timetree-mcp, viasocket.com/mcp/teamup-calendar, and the Junto connector in production. Cozi, TimeTree and Teamup member requirements are from their own pages, checked 2026-09-23.
A calendar holds when your group is meeting, where, and who is coming. An assistant that can read and change it should not need your login for the whole account.
Junto's connector is part of the product. You make a personal link inside the calendar, it acts only as you on that one calendar, only a hash of it is stored on the server, and you can disconnect or replace it at any time.
The community servers for Cozi and TimeTree are open-source projects by individuals. Their own pages say they are not affiliated with the companies, and both sign in with your account email or username and password. The TimeTree project also says the company's official API was discontinued in 2023 and that it uses private web endpoints that may change without notice. That is a fair trade for a tinkerer, and a reason for care if the account holds your family's plans.
The Cozi community server reads and updates both your lists and your calendar. It lists 15 tools by default, with a read-only mode of 6, and it says Cozi has no OAuth, so the username and password are the only way in. Cozi itself has lists, meals and chores that Junto does not.
Where Cozi falls short here: no official connector, a password in your setup, and a free calendar limited to a 30-day window with ads. See the Cozi alternative page for the price and limits.
The TimeTree community server runs on your own computer and signs in with your TimeTree email and password. It exposes 29 tools, including creating, updating and deleting events, and it can watch for changes. TimeTree itself has chat and unlimited free members, which Junto does not.
Where it falls short here: it is not official, it needs your password, and it relies on endpoints TimeTree could change. See TimeTree alternative.
Teamup has a third-party connector from viaSocket that lists five actions, including creating bookings and getting sub-calendars. Its page does not say how it signs in, and nothing on it says Teamup made it.
Teamup's own knowledge base says it does not currently offer an RSVP system, so an assistant has no answers to read. See the Teamup alternative page.
We would rather you hear it from us. Junto has no chat, no shopping lists, chores or meal plans, and no two-way sync with Google or Apple Calendar. It has no availability overlay.
On the assistant side, the connector cannot delete events, remove members, change settings, RSVP for other people or pay. Meta's Muse works too: its custom connector form takes a server URL and an API key, and the connector accepts both. Claude, ChatGPT and Claude Code work, although ChatGPT's menus change and we could not confirm its no-OAuth case from OpenAI's pages.
Asking an assistant to create a Junto calendar is free, and private calendars are free up to 8 members. Public calendars have no member limit and are free.
Letting the assistant read and change a calendar needs the unlock: $4.99 plus tax, one time, no subscription, per calendar. It also removes the 8 member limit. The assistant fetches the Stripe link and you pay it yourself.
Pick Junto if you want a group calendar with RSVPs that your friends open with a link, and you want an assistant connected without handing over a password. Pick Cozi if lists and chores matter more than connector quality. Pick TimeTree if chat and unlimited free members matter, and you are comfortable running a community tool.
If you already use one of the others, you can still try Junto alongside it with the free connector. Read how the connector works first.
See how the built-in connector works and add it to Claude or ChatGPT.
Several can be connected, but they differ in who built the connector. Junto has an official one built in. Cozi and TimeTree have unofficial community servers that use your account password, and Teamup has a third-party connector. Try the free connector in Claude or ChatGPT to see the difference.
We found none on 2026-11-06. The Cozi server we found describes itself as unofficial and not affiliated with Cozi. It signs in with your username and password. Junto compares differently: its connector is official and uses a revocable key. If you keep Cozi, treat that password setup with care.
We found none. The TimeTree server we found is a community project that is not affiliated with TimeTree and uses your email and password, and its README says TimeTree's official API was discontinued in 2023. Junto offers an official connector instead, so try it before trusting a password to a tool.
Through a third-party connector from viaSocket, according to its page, which lists five actions. It does not describe sign-in, and Teamup says it has no RSVP system. Junto has RSVPs, so an assistant can tell you who is coming. Check the viaSocket page before relying on it.
It depends on how it signs in. A revocable key limited to one calendar is safer than your account password. Junto uses the key, stores only a hash and lets you disconnect. Whatever you choose, keep the link private and replace it if it leaks.
Creating a calendar through an assistant is free, and private calendars are free up to 8 members. Letting an assistant read and change one needs the unlock: $4.99 plus tax, one time, no subscription, per calendar. Junto removes the member limit with the same payment. Try the free part first.
We left Google Calendar out because we could not verify its assistant support on Google's, Anthropic's or OpenAI's own pages. Junto does not sync with Google Calendar either way, so if you need your own Google events in the same place, it is not the right tool. Check the vendors' pages.
It depends on the connector. The Cozi and TimeTree community servers can delete, according to their pages. Junto's connector cannot delete events, remove members or change settings, so a mistake stays fixable by you in the calendar. Ask for confirmation before any assistant adds events.
Claude, ChatGPT and Claude Code can add a connector by URL, and Junto is built for that. Meta's Muse works too: its custom connector form takes a server URL and an API key, and the connector accepts both. For ChatGPT, the menus change, so read our ChatGPT guide first and then paste the link.
Junto did, so it has a stake. We stated the criteria first, quoted each connector's own page with the date checked, and listed what we lack. Check the sources yourself, and if a fact has changed, tell us through the help button so we can fix the page.
Sources
Last updated 2026-11-06