What do developers care about?

I'll start by saying - ask them! The best way to approach product marketing is to become intimately familiar with your personas. 

Having said that - remember also that developers are human beings. 

As such, when at work - they value (each prioritizing individually of course) the same things that everyone else does: 

- success at your job/the task at hand - finding the right code for the right goal 

- productivity and the ability to solve immediate issues as fast as possible - debugging easily; identifying points for improvement in your code

- quality of output - clean and efficient code 

- collaboration - working smoothly with the rest of the team and other stakeholders 

- learning and developing 

- mentoring each other 

When talking about product value prop, developers care more about:

• functional benefits (aka "features")
• security and owning the data
• transparent messaging around expected outcomes (no fuzzy marketing promises)