This article is from the Apple II GNO FAQ, by Devin Reade with numerous contributions by others.
A#13.1: There are no GNO-specific debuggers, however there are at least two
popular ones that are compatible with GNO.
If you are programming in C, it is highly recommended that you
purchase "Splat!", written by Michael Hackett of Some Assembly
Required. This is also available from Procyon. See also Q#13.2.
If you are programming in assembly, it is recommended that you
install GSBug. This comes bundled with ORCA/M and is also available
for download from the Apple Inc dts ftp site. GSBug has many
add-on packages used to increase its functionality. Two of these
are Niftylist and Nexus.
 
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