This documentation refers to Jira Data Center only.
Jira has REST APIs and Java APis that you can use to interact with Jira. For example, you may want to integrate your existing application with Jira or write a script to get information from Jira. For more information, check out our reference documentation:
The following authentication methods are supported for the Jira REST APIs:
Jira uses cookie-based authentication in the browser, so you can call the REST API from Javascript on the page and rely on the authentication the browser has established. To reproduce the behavior of the Jira log-in page, you can POST to the /auth/1/session resource. You can use it, for example, to display authentication error messages to users.
Atlassian's architecture documentation will help you understand Jira fundamentals and get a high-level perspective of Jira's dependencies.
It covers such topics as webhooks, web panels, web fragments, authentication, and templates.