Tool for creating new vocabulary

Hello, I’m looking for an online tool for creating new ontology, for Omeka S.
We need to have it online, so we can share the work.
Any suggestion?
Thank you

A colleague of mine uses:(https://protege.stanford.edu/)

Thanks for the suggestion. I tried it but I couldn’t make it works properly. And very little documentation available. I will give it an other try anyway.
But if you hear about other options, it would be great.

There’s a Custom Ontology module that will save the ontology on a webpage within your Omeka installation.

Yes I’m using it, but it doesn’t answer all our needs.
We are creating a whole new vocabulary, that is quite big. So we need to be able to update and to manage in an easier way. Plus I couldn’t find any way to extract the vocabulary I created.

Which webpage are you talking about, for saving the ontology?