Worked part-time over the course of a semester, acting as a system administrator and software developer for the ISSF (Information System on Small-scale Fisheries) app.
Primarily ensured the app stayed online, and resolved a few small bugs as they arose.
Prior to that, I spent a Christmas break there working on a contract to improve the app. During that time I (among other things):
Rewrote the site's search functionality to be more reliable and to return more relevant results
Discovered and resolved a number of security issues
Cleaned and documented all backend code, to help future developers work on the app
Added native PDF generation functionality to the app, so users could download PDF reports straight from the app