This study is testing a mobile app called Combine to see if it helps men in rural areas get tested for HIV and sexually transmitted infections (STIs) more often. Also, the app will share information about a medicine called PrEP that helps prevent HIV. Participants will have the app for 24 months and will be in one of four groups, including a control group that only uses the app. Other groups get extras like self-test kits or motivational talks. Researchers will compare these groups to decide what works best for increasing testing.

• Study lasts 24 months with app use.
• Participants must download and use a smartphone app.
• No medicine or physical visits required, only app interactions.

To join, you must be a male aged 18-34, live in the rural U.S. South or Missouri, and have a smartphone. Participants need to be willing to download an app, speak English, and report having had sex with a man in the past year. You should not be currently using PrEP and must be HIV-negative or unsure of your HIV status.