The free PC-HFDL v1.0 (unsupported version) can still be downloaded from the link below. It is not as spruced up as the full version but for decoding it will work just fine.
https://xoomer.virgilio.it/ham-radio-manuals/If you want to get into some serious decoding, grab a copy of Sorcerer. Many of us, including myself, wish this decoder was still being maintained.
http://www.kd0cq.com/2013/07/sorcerer-decoder-download/Some of the "bugs" in Sorcerer can be fixed by following the instructions here:
https://www.sigidwiki.com/wiki/High_Frequency_Data_Link_(HFDL)The Sig ID Wiki page provides reference on how to correct the HFDL system table under "How to correct the site displays in Sorcerer". The procedure is correct, but the system table given on that site is out of date. HFDL is currently on system table #51. Below is the proper table to use:
UNKNOWN0
SAN FRANCISCO - CALIFORNIA
MOLOKAI - HAWAII
REYKJAVIK - ICELAND
RIVERHEAD - NEW YORK
AUCKLAND - NZ
HAT YAI - THAILAND
SHANNON - IRELAND
JOHANNESBURG - SOUTH AFRICA
BARROW - ALASKA
MUAN - SOUTH KOREA
ALBROOK - PANAMA
UNKNOWN12
SANTA CRUZ - BOLIVIA
KRASNOYARSK - RUSSIA
AL MUHARRAQ - BAHRAIN
AGANA - GUAM
CANARIAS - SPAIN