Chartio connects to Heroku PostgreSQL databases with great ease. You'll simply need to retreive the connection URL from the database's admin page. For more details follow these connection steps.
On its page, open the Connection Settings menu pictured below and select URL
Copy the URL listed. It should look something like
postgres://u82383j44k:p7s3tp2sf8sdf11bu471n056@ec2-88-991-76-136.compute-1.amazonaws.com:5792/d163qdfjfdsq37
On Chartio navigate to your settings and click + New Data Source
Copy the URL from Heroku, paste it into the input box in Chartio, and submit.
Heroku wisely enables PostgreSQL SSL connections by default. Every data connection Chartio makes is encrypted this way.