How to promote Affiliate Program?

We've added an affiliate program to TestingBot (TestingBot provides testing in the cloud on browsers & mobile devices): https://testingbot.com/affiliate-program

People can sign up, refer other people and receive a 30% commission on recurring monthly subscriptions.

What are some of the ways to promote this new affiliate program? We've submitted the program to a couple of affiliate program directories, wondering if there are other ways to get attention to this?