Official support for iReport ended in 2015, but you can still access the archived versions through community-maintained repositories:
: If you specifically need the associated library, you can download the jasperreports-5.1.0.jar . New Features in Version 5.1.0 download jaspersoft ireport designer 5.1.0
Using a legacy tool like iReport 5.1.0 in a modern environment comes with several significant challenges. It is crucial to be aware of these limitations. Official support for iReport ended in 2015, but