The Altmetric API documentation can be found here: Altmetric API Documentation.
The Altmetric API gives you programmatic access the data about research outputs and datasets collected by Altmetric.
What can you do with the API?
It's free to use the API to fetch basic altmetrics information about research outputs and to use that information in your own apps and mashups - just give altmetric.com attribution somewhere.
However, if you'd like to download the data in bulk, perform more complex queries, remove the rate limits and see more detailed data about articles then you'll need a commercial license (if you'd like to let us know about your use case you can reach us at firstname.lastname@example.org).
If you'd like to use the data in an academic research project then let us know and we can grant you a free license for non-commercial use.
Want to see some examples of what's possible? Check out our API gallery.