Hi @dw if you start a board and invite someone they will need to have an account (unless it is a public board that you created and then they can view only). They would be a member. Observers are part of the business class and enterprise Trello plan. Here is a link that explains all of the types of members:
If you create teams, you can have up to 10 free teams. Here is an article that explains this in further detail:
Here is an article that explains the difference in the plans and the pricing:
Hope this helps.
Hi @dw that depends how you are setting it up. If it is just 20 personal boards that you have invited 100 different people to view or join, I belive you could do that with a free account (however you may want to doube check). I encourage you to reach out to email@example.com to determine the best option for you, for example Trello Business class would give you unlimited powerups and a much large size for document upload.
Hello Community! My name is Brittany Joiner and I am a Trello enthusiast and Atlassian Community Leader. I'll be sharing with you a series of videos with my top tips on how to best use Trello...
Connect with like-minded Atlassian users at free events near you!Find an event
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no Community Events near you at the moment.Host an event
You're one step closer to meeting fellow Atlassian users at your local event. Learn more about Community Events