Yes. Aevo, 11MHz, Wekan, OpenProject, Teamwork and MeisterTask are free or have a free plan, according to the pricing each company publishes. Free plans usually carry limits; each product page links to the company's terms.
Which European project management tools are open source?
Wekan and OpenProject publish their source code under an open-source licence. Each product page shows the licence and where the code is.
Which European project management tools can you host yourself?
Wekan, OpenProject and Stackfield can be run on your own servers, according to their own documentation.
