If you have a PHP developer on staff and a fear of monthly recurring bills, the self-hosted, source-available Bitrix24 is the most powerful "open" collaboration suite you have never looked at.
The is frequently mislabeled as “open source” because you can view and edit the source code. However, legally it is source-available, not open source . bitrix24 open source
Developers, budget-conscious CTOs, and privacy-focused entrepreneurs frequently search for this term. They want the power of Bitrix24 but with the freedom, transparency, and zero licensing costs of open-source software. If you have a PHP developer on staff