ClickRepair is described as 'mature, well-tested, application for declicking and decrackling audio in uncompressed audio files. It has been developed over a period of many years. Cross platform. Requires Java run-time environment to run. Free fully functioning trial for 21 days'. There are five alternatives to ClickRepair for Windows, Mac and Linux. The best alternative is Adobe Audition. It's not free, so if you're looking for a free alternative, you could try GTK Wave Cleaner or Wave Corrector. Other great apps like ClickRepair are Sound Forge (Paid) and GoldWave (Paid).
GTK Wave Cleaner (formerly Gnome Wave Cleaner) is a digital audio editor application. The graphical user interface for the editor has been produced employing GTK+ for the GUI widgets. Its primary author is Jeff Welty.
Wave Corrector offers an integrated solution to record, clean-up and convert your music to digital audio formats. The program uses advanced digital processing to remove noise from old analogue recordings.