VarAC is one of the newer additions to the digital mode toolbox, and it’s easy to describe by comparison: it does for VARA roughly what JS8Call did for FT8, turning a weak-signal modem into a genuine keyboard-to-keyboard chat platform with modern conveniences built in.
Built on top of VARA, not a replacement for it
VarAC runs on top of the same VARA modem Winlink relies on, but instead of routing you through email-style messaging, it gives you a live chat interface with a buddy list showing which stations are currently active and reachable. That structure makes it feel far more like an instant messenger than a traditional ham digital mode, which is exactly the appeal for a lot of newer operators who grew up with chat apps rather than packet BBSs.
File transfer and more than just text
Beyond basic chat, VarAC supports file transfer, position reporting, and automated CQ calling with configurable macros, giving it a broader feature set than most single-purpose digital modes. It leans on VARA’s error correction to keep those transfers reliable even in mediocre band conditions, which is a real advantage over older, less resilient file transfer approaches.
VarAC vs JS8Call
The comparison to JS8Call is inevitable, since both aim to turn a weak-signal mode into a genuine messaging platform. JS8Call has the larger, more established user base and works over a wider range of marginal conditions since it’s built on FT8’s underlying sensitivity. VarAC, riding on VARA, tends to offer faster throughput and a more polished chat experience when band conditions are decent. I’d treat them as complementary rather than competing: JS8Call for the worst conditions, VarAC when you want a smoother, faster chat experience and the band cooperates.
Related reading: What Is VARA? · ARDOP vs VARA · Pat Winlink Client