GoProof provides an option to proof senders allowing them to only let collaborators view the proof if a password has been entered.

Before proceeding, please ensure that you are familiar with Sending a Proof - The Basics

Step 1.
From the Send Proof Wizard, select the Enable password protection for this proof checkbox option found in the Make Proof Confidential section.

Step 2.
Follow the next steps to send your proof.

Note: Once the collaborators access the proof via the email invitation link, they will be redirected to the GoProof login page to set their password if it is their first invitation to view a confidential proof.

Note: If you are sending the proof via Upload Proof on the website, the Make Confidential section will look slightly different.