This is way more confusing than it needs to be, but here’s how I was able to grant a Jira user access to only one project in JIRA.
Step 1: Create a new user in the User Management section of the Administrator. For this example, we’re just using username: test and email: [email protected]. Now, remove all of the Groups from this user. This means remove Jira-User and Jira-Developer. Jira-User will give the user access to all projects, which is not what we want. We should now have a user who can’t even login to JIRA good.

Step 2: Create a new group in the Administrator section. Entitle this new group TestGroup.

Step 3: Navigate to JiraAdministrationGlobal Permissions.

Step 4: Add your Test Group to Permission JIRA Users

Step 5: Your TestGroup should show up under JIRA Users

Step 6: Navigate back to the User Management Administration setting. Find the new user. Add only the TestGroup to the new user Test.

Step 7: Navigate to your Project in the Administrator mode. Add your new Group to one of the existing Roles, e.g. JIRA Users.

Step 8: Logout of JIRA as Administrator. Log back in with the new User. You should only have access to your Project!

Joel Garcia has been building AllCode since 2015. He’s an innovative, hands-on executive with a proven record of designing, developing, and operating Software-as-a-Service (SaaS), mobile, and desktop solutions. Joel has expertise in HealthTech, VoIP, and cloud-based solutions. Joel has experience scaling multiple start-ups for successful exits to IMS Health and Golden Gate Capital, as well as working at mature, industry-leading software companies. He’s held executive engineering positions in San Francisco at TidalWave, LittleCast, Self Health Network, LiveVox acquired by Golden Gate Capital, and Med-Vantage acquired by IMS Health.