Apps / Programms

Test your sound track online at (free)
Measure you files with
LAP (free)
Loudness-correct your files in batch with
WinLoud (free)
Edit audio files and Loudness-normalise with
Audacity (free)

Further reading

ITU Recomendations, the reference about Loudness: BS.1770
EBU Loudness page, the famous R128

Loudness Explained by TC Electronic
Broadcast Standards, TC Electronic

The Audio Producer’s Guide To Loudness by Rob Byers