Monday, September 20, 2021 · 3 min read

Changing to AGPLv3 and introducing the Enterprise Edition

Bailey Pumfleet
Bailey PumfleetCo-Founder,
Changing to AGPLv3 and introducing the Enterprise Edition

Changing to AGPLv3 and introducing the Enterprise Edition

What is Open Source Licensing and why does use it?

Ever since the inception of Calendso, we’ve used an open source license to allow our community to access, contribute and deploy our product.

Open source also allows us to build our product with a high quality thanks to more eyeballs of engineers peer-reviewing code, adding new features that the community have requested faster and, most importantly, it offers a way for the community to contribute to the codebase.

However, being open-source as MIT also exposes us to certain risks that we’ve now become aware of with the massive recent growth of our product.

We’ve seen open source projects being devoured by big tech companies in the past, who were licensed under MIT and with AGPLv3 we’ve found a better license to protect our community efforts and interest.

What is AGPLv3 and how does the Cal community benefit?

As a result of the AGPLv3 license, is able to release all code to the community as open source while retaining more control over the brand, credits and material.

There'll be no changes for paid hosted users or self-hosted users by changing from MIT license to AGPLv3 and its copyleft license:

“If you make a derivative work of this, and distribute it or run it as a service on a server to others then you have to provide the source code under this license”

The team at wrote an excellent piece on the benefits:

AGPL is designed to ensure corporations contribute back to the open source community even when running the software as a service in the cloud.If you used AGPL-licensed code in your web service in the cloud, you are required to open source it. It basically prevents corporations that never had any intention to contribute to open source from profiting from the open source work.It explicitly prohibits corporations from parasitically competing with an open source project. They won’t be able to take the code, make changes to it and sell it as a competing product without contributing those changes back to the original project.

Free Software Foundation (FSF) and the GNU project state:

“We recommend that people consider using the GNU AGPL for any software which will commonly be run over a network”.


“If it is likely that others will make improved versions of your program to run on servers and not distribute their versions to anyone else, and you’re concerned that this will put your released version at a disadvantage, we recommend the GNU Affero General Public License (AGPL). The AGPL’s terms are almost identical to the GPL’s; the sole substantive difference is that it has an extra condition to ensure that people who use the software over a network will be able to get the source code for it.”

Open-sourcing our Enterprise Edition

Additionally, we’ve decided to open-source our Enterprise Edition (short “/ee”) in the upcoming days. That includes features such as SSO, SAML, ADFS, OIDC, SCIM, SIEM, HRIS and more. The code base of the /ee version is licensed under our Enterprise License which you can obtain on our enterprise website.

The content of the /ee folder is copyrighted and you are not allowed to use this code to host your own version of without obtaining a proper license first.

However, open-sourcing the content brings even more transparency to our product suite and really shows that there are no unknown-unknowns, caveats or backdoors in the commercial and proprietary part of our business.

It also improves the security as researchers can peer-review code in the enterprise edition, which was previously closed source.


  • Today, we’re changing our license from MIT to AGPLv3 to protect our community and ensure the longevity of Cal.

  • For you, nothing will change.

  • Open-sourcing our enterprise edition in the upcoming weeks

Thank you for being part of the MIT licensed journey, the next AGPLv3 adventures are ahead!

Bailey is now FREE for individuals - sign up here

Related Articles

Let people book when it works for both of you