This is more of a plugin rather than a 3rd party service that uses an API.
Although we haven’t built any of this, our ideal platform contains API and then a plugin system. API is anything that pulls Dynalist data for use on a 3rd party, where the plugin system makes it possible to modify the look and feel of Dynalist, and even how Dynalist works.
Unfortunately we haven’t finished with polishing the core product yet, and currently we’re working on scaling infrastructures, so this entire platform thing has to wait for now. Even when we do start it, it’s going to be a pretty big project. So, sorry, there’s no official way to do it right now.
Writing a Chrome extension could work, or write a JavaScript file that modifies Dynalist, like Powerpack.