A free Microsoft Teams alternative for people who run client sessions, classes and groups on video
On Teams, a client joins on Microsoft's page, marked Unverified, under rules your IT admin sets. With Castio, clients meet you at your own address, like meet.yourfirm.com, and there are no per-seat fees. Below, the two side by side.
Free software
No per-seat fees
Add as many hosts and members as you like.
No 60-minute cap
Meetings run as long as you choose, up to 24 hours. Permanent rooms stay open.
Up to 1,000 people per meeting
You set the limit.
Links on your own domain
Like meet.yourcompany.com, when your domain is on Cloudflare.
What you'd pay Microsoft Teams for
Each of these is included in Castio's software. On Microsoft Teams, it takes a paid plan, or it isn't offered.
Group meetings longer than 60 minutes
CastioIncluded
Microsoft TeamsTeams Essentials, $4 a user a month, paid yearly. Source: Microsoft Teams (free)
Recording
CastioIncludedRecordings are saved for 7 days by default; turn on one setting and they're kept in your own Cloudflare storage until you delete them.
Microsoft TeamsTeams Essentials, $4 a user a month, paid yearly. Source: Microsoft Teams Essentials
Your logo and colors
CastioIncluded
Microsoft TeamsTeams Premium, $10 a user a month paid yearly, on top of a Teams license. Source: Microsoft Teams Premium
Meetings with more than 300 people
CastioIncluded
Microsoft TeamsNot on Teams Essentials, which stops at 300. Up to 1,000 takes an enterprise or frontline plan, such as Office 365 E1 at $10 a user a month, paid yearly. Source: Microsoft Office 365 E1
Teams plans and prices as their own pages state them, checked 9 October 2026.
What Microsoft Teams has that Castio doesn't
Castio doesn't have breakout rooms. It runs in any browser, with nothing to install.
Microsoft Teams vs Castio, side by side
Scroll sideways for the Castio column →
| Category | Microsoft Teams |  Castio |
|---|---|---|
| Price | $4 a user a month (Teams Essentials, paid yearly), so $40 a month for 10 users | $0 per user; about $5 a month in total to Cloudflare for the same team, plus $149 a year for us to install it today. How we worked it out |
| Source code | Closed | Going open source; code goes public with the free self-install version |
| Clients joining | Guests can join in a browser without an account. They're marked Unverified and wait in the lobby, and an admin setting can block them. | No Unverified label, and no Microsoft admin setting decides who gets in. You choose whether a waiting room is on. |
| Branding and address | Microsoft's brand on a teams.microsoft.com link. Teams Premium, $10 a user a month on top of a Teams license, adds your logo and colors on the pre-join screen and lobby; the link stays on Microsoft's domain | Your logo and colors, at your own address, like meet.yourfirm.com |
| Cost as you add hosts | Per user. Teams Essentials is $4 a user a month, paid yearly. | No per-seat fees. Every host is included. Cloudflare's bill follows meeting minutes, not hosts. |
| Large meetings | Up to 300 people on Teams Essentials. Up to 1,000 on enterprise and frontline plans, such as Office 365 E1 at $10 a user a month, paid yearly. | Up to 1,000 people in a meeting or webinar (100 by default; you set the limit), plus a public livestream page. |
Setting it up
We install it for you on your own Cloudflare account and domain. You need a Cloudflare account on its Workers Paid plan, and your domain has to use Cloudflare for its DNS.
What people usually mean by "microsoft teams alternative"
A Microsoft Teams alternative for external guests
Teams is built for people inside a Microsoft 365 organization. By default, someone outside it can still join a meeting from the link without an account, in a browser. They show up as Unverified and wait in the lobby until someone lets them in. If nobody does within 30 minutes, Teams removes them.
Whether that works depends on settings an admin controls. If IT has switched anonymous join off, clients need an account to get in. That's a decision for IT, not for the person hosting the client meeting.
A branded, client-facing alternative to Teams
Some searchers aren't leaving Microsoft 365 for internal work. They just don't want client calls on a Microsoft page with Microsoft's name on it. Castio runs those calls at your own address, with your logo, colors and favicon on the pages your clients see.
Where Castio differs from Teams
Teams is part of Microsoft 365 and built for an organization's own members first. Outside guests come in under that organization's policies. Castio is installed into your own Cloudflare account and runs at your own address. Clients click a link or enter a meeting code and join in the browser. No account, no app, and no Unverified label. You decide per meeting whether they wait in a waiting room first.
Microsoft 365 charges per user, per month, bundled with email and Office. Castio is the meeting platform alone, with no per-seat fees for any host.
What the numbers say
Microsoft 365 Business Basic, which includes Teams, is $7 a user a month paid yearly: $840 a year for a team of 10.
Teams Essentials is $4 a user a month, $480 a year for 10 users, but your clients still land on Microsoft's page. Castio has no per-seat fees for any host. Cloudflare bills you directly for the meetings you hold: the price row above shows the same 10-person team, and what Cloudflare costs has the arithmetic.
Questions people ask
What is a good alternative to Microsoft Teams for client meetings?
Castio, for client calls at your own address and in your own brand, where every client joins the same way.
Can external users join a Teams meeting without a Microsoft account?
Yes, by default. They join from the link in a browser, marked Unverified, and wait in the lobby until someone admits them. If nobody does within 30 minutes, they're removed. An admin can turn anonymous join off.
Does the free version of Microsoft Teams have a time limit?
Yes. Teams (free) runs one-on-one calls for up to 30 hours and group meetings for up to 60 minutes. Castio has no 60-minute cap: the host picks each meeting's length, up to 24 hours, and the meeting ends at that time.
Sources
Facts about other products were checked against their own pages in September and October 2026.
- Microsoft Learn: anonymous users in Teams meetings
- Microsoft Support: join a Teams meeting without a Teams account
- Microsoft Teams (free)
- Microsoft Teams Essentials
- Microsoft Teams Premium
- Microsoft Learn: meeting themes
- Microsoft Learn: limits and specifications for Teams
- Microsoft Office 365 E1
- Microsoft 365 business plans compared
Free to run. Yours to keep.
Have us install and update it, or install it yourself for free once the code is public.
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