Yep, at a place I used to do work for I used their API to build a number of time saving things, all of which were tiny shell scripts.

Like adding a custom text field to each ticket with a human description of what a ticket did which someone would fill out along with a timestamp that got auto-filled out when a release shipped (deploy script). We'd release 1 ticket at a time as a line of work (many tickets per day). This combined with custom filters resulted in Jira providing us a human readable changelog for each board and the whole company. These messages were Slacked to the business so everyone had a pulse on what was going live. It was also a searchable audit log of all releases, tying back to a code change.

The deploy process also transitioned Jira tickets so a developer never had to do anything more than merge a ticket to main to have it get deployed and completed on Jira.

Lots of little scripts that automatically created tickets for routine tasks, etc..

It was super solid for years and I'm going to guess it's still running today. The naming conventions of the custom fields were lame but if your team is in control of setting up Jira, it wasn't hard to keep everything on the same page.

I started off not liking Jira and it had a lot of issues many years ago but it's actually not that bad nowadays once you set it up. I wouldn't choose it for my own company but as a developer and someone who has administrated it, used it as an end user and developed against it for internal tools, it mostly gets out of your way once it's configured and working.