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EULA for Kirby 4: Summary of changes

Kirby 4 was released on November 28, 2023 with a new licensing model. We updated our license agreement (EULA) to reflect this.

The updated terms are binding for all newly purchased licenses and license upgrades for Kirby 4+.

In particular, we have changed the following:

New licensing model

Together with Kirby 4, we introduced a new yearly major release schedule to bring continuity and planning security.

To avoid yearly upgrades or subscriptions, we have decided on a new licensing model that includes free feature updates for at least three years from the initial activation of the license. During this time, new major versions are no longer bound to a paid upgrade.

After those three years, you can continue to use Kirby for your project with any of the included versions as long as you want.

To use any newer version released after this time, you will need to upgrade your license. Upgrading your license extends the timeframe for an additional three years during which you can use new releases. You can perform the upgrade at any time.

The new EULA reflects this new licensing model with new "Major Generation", "Activation Date" and "Included Updates Period" terms and their use in the relevant sections of the agreement.

New license types

Kirby 4 is available in two different license types (Basic and Enterprise). We state the requirements for each license type on our Buy page.

The new EULA includes language that makes these requirements binding on each license purchase, upgrade, transfer and reassignment.

Additional changes

Your rights

  • We have already provided security updates for older Kirby versions in the past. The new EULA now codifies security updates for three years from the release date of each major release (e.g. Kirby 4.0, Kirby 5.0 etc.). A newly purchased or upgraded Kirby license will therefore receive up to six years of security support.
  • Based on your feedback, we have added a clause that protects you in the event that Kirby will no longer be actively maintained. In this case, we will provide Kirby's code under the terms of a free and open source (FOSS) license.

License restrictions

  • Licenses already needed to be activated to the site's domain in Kirby 3. This is now a requirement for using Kirby in production because the update duration of the license depends on the activation date.


  • The updated EULA now features a Summary section for easier understanding.
  • We renamed the terms "Update" and "Upgrade" to "Minor Release" and "Major Release" to avoid confusion with upgrade purchases. Both release types are now defined as stable releases because the initial stable release of each major release is relevant for the included updates period.
  • We clarified that major releases may contain functionality changes, deprecations and breaking changes, as is common to ensure the continued software development and improvement.
  • We have also made minor editorial changes that don't change the general meaning of the EULA.