The GNU Visual Debugger (GVD)
- Written in Ada as a front end to GDB and other debug programs.
- https://libre.adacore.com/gvd/

Microsoft Debugging Tools
- Downloads and related resources for debugging tools for Windows.
- http://www.microsoft.com/whdc/devtools/debugging/

SmartInspect
- A logging tool for debugging and monitoring .NET, Java and Delphi applications. [Commercial, free personal edition for non-commercial use]
- http://www.gurock.com/products/smartinspect/

HP WDB Debugger
- An HP-supported implementation of the GNU GDB debugger.
- http://www.hp.com/go/wdb

Fx2
- Debuger for Fortran, C, C++, assembler. It can work with compilers from multiple vendors. By ABSOFT Corporation. [Commercial]
- http://www.absoft.com/Products/Debuggers/fx2/fx2_debugger.html

GDB: The GNU Debugger
- Allows debug programs written in C, C++, and other languages, by executing them in a controlled fashion, and printing their data, on a wide variety of UNIX and non-UNIX systems.
- http://sources.redhat.com/gdb/

Sankhya Tools for Software Development
- Sankhya Simulator, a retargetable Instruction Set Simulator that loads ELF/DWARF and S-Record Files; Sankhya Debugger, a simple assembly level system debugger.
- http://www.sankhya.com/info/products/tools/simulator.html

Auto Debug System
- An auto-tracing tool to spy Window API and COM Interface calls.
- http://www.autodebug.com/

Etnus - Debugging Tools
- Developer of Totalview, a tool which aids in the development of multithreaded, multiprocess and network-distributed applications.
- http://www.etnus.com/

Spline Technologies Corporation
- Offers debuggers for ASP, JavaScript, and VBS. Information available on features and system requirements as well as an online demo. [Commercial]
- http://www.remotedebugger.com/

DDD - Data Display Debugger
- A graphical X Window front-end for command-line debuggers such as GDB, DBX, WDB, Ladebug, JDB, XDB, the Perl debugger, or the Python debugger.
- http://www.gnu.org/software/ddd/