Debugging Environments

There are six available debugging environments:

  • WinDbg Preview
  • Windows Debugger (WinDbg)
  • Kernel Debugger (KD)
  • NTKD
  • Console Debugger (CDB)
  • NT Symbolic Debugger (NTSD)

The following sections describe the debugging environments.

WinDbg Preview

WinDbg Preview is the latest version of WinDbg with more modern visuals, faster windows, a full-fledged scripting experience, built with the extensible debugger data model front and center. WinDbg Preview is using the same underlying engine as WinDbg today, so all the commands, extensions, and workflows you're used to will still work as they did before.

For more information, see Debugging Using WinDbg Preview


Microsoft Windows Debugger (WinDbg) is a Windows-based debugger that is capable of both user-mode and kernel-mode debugging. WinDbg provides debugging for the Windows kernel, kernel-mode drivers, and system services, as well as user-mode applications and drivers.

WinDbg uses the Visual Studio debug symbol formats for source-level debugging. It can access any symbol or variable from a module that has PDB symbol files, and can access any public function's name that is exposed by modules that were compiled with COFF symbol files (such as Windows .dbg files).

WinDbg can view source code, set breakpoints, view variables (including C++ objects), stack traces, and memory. Its Debugger Command window allows the user to issue a wide variety of commands.

For kernel-mode debugging, WinDbg typically requires two computers (the host computer and the target computer). WinDbg also supports various remote debugging options for both user-mode and kernel-mode targets.

WinDbg is a graphical-interface counterpart to CDB/NTSD and to KD/NTKD.


Microsoft Kernel Debugger (KD) is a character-based console program that enables in-depth analysis of kernel-mode activity on all NT-based operating systems. You can use KD to debug kernel-mode components and drivers, or to monitor the behavior of the operating system itself. KD also supports multiprocessor debugging.

Typically, KD does not run on the computer being debugged. You need two computers (the host computer and the target computer) for kernel-mode debugging.


There is a variation of the KD debugger named NTKD. It is identical to KD in every way, except that it spawns a new text window when it is started, whereas KD inherits the Command Prompt window from which it was invoked.


Microsoft Console Debugger (CDB) is a character-based console program that enables low-level analysis of Windows user-mode memory and constructs. The name Console Debugger is used to indicate the fact that CDB is classified as a console application; it does not imply that the target application must be a console application. In fact, CDB is fully capable of debugging both console applications and graphical Windows programs.

CDB is extremely powerful for debugging a program that is currently running or has recently crashed (live analysis), yet simple to set up. It can be used to investigate the behavior of a working application. In the case of a failing application, CDB can be used to obtain a stack trace or to look at the guilty parameters. It works well across a network (using a remote access server), as it is character-based.

With CDB, you can display and execute program code, set breakpoints, and examine and change values in memory. CDB can analyze binary code by disassembling it and displaying assembly instructions. It can also analyze source code directly.

Because CDB can access memory locations through addresses or global symbols, you can refer to data and instructions by name rather than by address, making it easy to locate and debug specific sections of code. CDB supports debugging multiple threads and processes. It is extensible, and can read and write both paged and non-paged memory.

If the target application is itself a console application, the target will share the console window with CDB. To spawn a separate console window for a target console application, use the -2 command-line option.


There is a variation of the CDB debugger named Microsoft NT Symbolic Debugger (NTSD). It is identical to CDB in every way, except that it spawns a new text window when it is started, whereas CDB inherits the Command Prompt window from which it was invoked.

Since the start command can also be used to spawn a new console window, the following two constructions will give the same results:

start cdb parameters
ntsd parameters

It is possible to redirect the input and output from NTSD (or CDB) so that it can be controlled from a kernel debugger (either Visual Studio, WinDbg, or KD). If this technique is used with NTSD, no console window will appear at all. Controlling NTSD from the kernel debugger is therefore especially useful, since it results in an extremely light-weight debugger that places almost no burden on the computer containing the target application. This combination can be used to debug system processes, shutdown, and the later stages of boot up. See Controlling the User-Mode Debugger from the Kernel Debugger for details.

Windows Debugging

Debugging Using WinDbg Preview