Software

What each program is actually for. Nearly all of it is free, and most of it runs on Windows, macOS, Linux and a Raspberry Pi.

Weak-Signal Digital

WSJT-X: FT8, FT4, WSPR, JT65, Q65 and more. The reference implementation, free and cross-platform.
JTDX: An alternative FT8/FT4 program derived from WSJT-X, favored by some operators for its decoder in crowded conditions.
GridTracker: Sits alongside WSJT-X and maps what you are hearing and working. Not required, but hard to give up.

fldigi: PSK31, RTTY, Olivia, MFSK, Hell and a long list of others in one program. The Swiss army knife of HF digital.
JS8Call: FT8-style robustness with free-form messaging and store-and-forward relaying.
MMSSTV: The long-standing Windows program for slow-scan television.

Direwolf: A software TNC using your sound card. Decodes better than most hardware TNCs and runs happily on a Raspberry Pi.
BPQ32 / LinBPQ: Node, bulletin board and mailbox software for packet networks, on Windows and Linux. Links over radio and over the internet.
UZ7HO soundmodem: A lightweight Windows software TNC, widely used for packet and APRS.
YAAC: Yet Another APRS Client — cross-platform, Java, full-featured mapping.
Xastir: The long-established APRS client for Linux.

Winlink Express: The standard Windows client for the Winlink email network.
Pat: A cross-platform, open-source Winlink client that runs well on Linux and small computers.
VARA HF / VARA FM: The modem software most Winlink HF and FM connections now use. Commercial, with a limited free mode.

Software moves faster than any printed guide. If something here has gone stale or a link has died, let us know and it gets fixed.

Independent, non-commercial. Not affiliated with the FCC or ARRL.