How to sell to developers:

1. Go to your local Hackerspace (or makerspace). If you don't have a Hackerspace in your city - create one.

2. Sit there with your target audience. Don't be pushy.

3. Solve their problem with your solution, in real-time.

Also, you should spend like half of my time on Meetup.com and try to attend all possible dev-oriented events where you could pitch my product. Time consuming, but rewarding. Worked with https://aidlab.com/developer