No, users do not need to sign in / register to post to a Kudoboard. If you'd prefer not to create an account and stay anonymous you're welcome to choose "Skip Email" and add as a guest.
The only exception is when users are posting to boards created through Business & Enterprise plans; in this case, they are required by default to register before posting.
To post using the Skip Email option:
1. Open the board.
2. Click + Add to Board in the bottom right-hand corner.
3. Create your post by adding text and/or media and then clicking Next.
4. On the next screen, click Skip Email in the upper right-hand corner.
5. Confirm that you'd like to skip the email registration process by clicking Skip email once more.
6. Enter the first and last name that you'd like to appear in the signature line of your post, then click Post. You're all done!