Do we have a password grant API in JIRA that responds with the OAuth Token?

I’m working on a project where I’ll be using JIRA as my bug tracker ( issue tracker ). My employees will be able to track issues here. However, I have a custom support page, where my employees will be able to sign in with their JIRA credentials (this is a custom login page and not a JIRA login page ). How can I get this user ID/Password authenticated? is there an API that responds with an OAuth token in return for success of this credentials being correct?