In an effort to shrink the global AIDS epidemic, the world’s largest gay dating app is changing its software this week to urge millions of users to get frequent H.I.V. tests.

Grindr, which claims to have 3.3 million daily users from every country in the world, will send men who opt into the service a reminder every three to six months, and simultaneously point them to the nearest testing site. It will also let clinics, gay community centers and other testing sites advertise for free.

The company is making the move to “reduce H.I.V. transmission and support our whole community — regardless of H.I.V. status — in living long and fulfilling lives,” said Jack Harrison-Quintana, Grindr’s director for equality.

H.I.V. experts greeted the announcement enthusiastically.

“Wow — that’s great!” said Dr. Jeffrey D. Klausner, a former chief of sexually transmitted disease prevention in San Francisco who has used Grindr to promote testing. “For a company of this magnitude to do this is groundbreaking.”Dr. Klausner has studied using Grindr to distribute H.I.V. home-test kits to gay black and Hispanic men, who are the country’s highest-risk group.

Numerous studies, he said, have shown that reminders by text or phone can triple or even quadruple the chance that the recipient will get tested.

But few men, Mr. Harrison-Quintana said, will download health-oriented apps that make them feel shamed for missing a test.