trello
I have a business using Trello with my team. I would like to allow them to add content, upload, comment but prevent them from deleting or changing what I have written.
I use the free version but would buy an upgrade (which one do I need?) if the option is available.
As of November 21 2014, Trello allows you to add unlimited labels:
http://blog.trello.com/introducing-unlimited-labels/
They will be unassigned from cards, and that's about it. Their actions will be preserved, as will the fact that they performed the actions.
Best Answer
In the free version there are only two types of roles - Members and Admins - both of which are allowed to change/delete content from cards, so this will not work for you.
The Observer role in the Business Class (paid) version might work for you. Trello help documentation describes the Observer role as:
However, if you couple this up with configuring the Commenting Permissions such that Observers are allowed to comment in cards, then you've got yourself a role that is essentially read-only but with the ability to add comments to cards (keep in mind that a comment can be text, link to another card, or attachments)
So in short, an Observer role configured correctly in Business Class gives you a user role that cannot change/delete what you have written but allows them to add text and attachments through comments on the card. They also will not be able to add new cards.