Since January 2015 I've been working for Contentful
, a CMS which puts developers first, not WYSIWYG first. They built the product around an API — quite a innovative idea, admittedly — which made developers fall in love with it instantly.
I've developed the tone of voice and written the house style guide, created the website out of nothing, significantly contributed to content strategy, wrote plenty of ad campaigns, and came up with a ton of jokes on the way.
All of these activities led to significant growth of the audience throughout every channel and a massive increase in visitors engagement, percentage of signups, daily active users and paying customers. The numbers are impressive; too bad I can't show them here, because NDA.
See some selected examples below.