Client for Jira (formerly known as Jira Client) is now an open-source product!
As of May 2020, new feature development for this product has ceased and support for it is limited. The details are available in the Jira Client Reference.
Consequently, we've recently made the product available in open-source form. And, for those who want to continue using the product as is, there is a free, unsupported version available via the button below.