Did you get paid? If so, I think "contract work" is an appropriate description. You might not have had a formal contract, but you had an agreement that they would pay you for your efforts. If you didn't get paid, I would list it as "volunteer work."
Also, fyi - it looks like there is a typo in this sentence - "This project liked authorities all around Europe and North Africa " - linked maybe?
the project was developed for governments in Europe and north Africa, it means that after see the A version of the software they wanted participated.....I went to the countries and I talked with them then they liked the idea and start cooperating, we used to work using SCRUM we develop and they check it.
I had a contract as ranger in a campament the tittle was Monitor and inside my activities(take care of a campament) I did that because the town hall wanted to install that software inside campament and in others campaments in Europe. For example I had a contract for 1 month as ranger then I used to keep an eye and develop software, take requirements etc...the other month nothing(i had no contract) then I as volunteer used to work more on it becasue I wanted learn and make it a success after four years of activity the association which was resposible of all was freeze. (no money)