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+=====================
+Building NSIS Plugins
+=====================
+
+.. note::
+
+  This guide assumes that you have a Firefox build environment set up as well as a recent version of Visual Studio. The steps here use Visual Studio 2022.
+
+Instructions
+------------
+
+1. Make sure you are configured to build DLLs. Follow this `guide <https://learn.microsoft.com/en-us/cpp/build/walkthrough-creating-and-using-a-dynamic-link-library-cpp>`_.
+2. NSIS plugins are not integrated with the build system pending `bug 1771192 <https://bugzilla.mozilla.org/show_bug.cgi?id=1771192>`_. You will need to build them manually by creating a new Visual Studio project in the ``$SRCDIR/other-licenses/nsis/Contrib/`` directory with the following settings.
+
+.. image:: newProjectDllVS.png
+.. image:: projectSettingsDllVS.png
+
+3. Once the project has been created, right click on it in the sidebar and go to ``Configuration Properties -> C/C++ -> Precompiled Header`` and set ``Precompiled Header`` to "Not Using Precompiled Headers".
+
+.. image:: projectPropertyPageVS.png
+
+4. For easier testing set the output directory in ``Configuration Properties -> General`` to ``$SRCDIR/other-licenses/nsis/Plugins``.
+
+5. Delete any files generated when you created the Visual Studio project such as ``pch.h`` or ``framework.h`` and any related include statements.
+
+6. Download the source code for `NSIS version 3.07 <https://sourceforge.net/projects/nsis/files/NSIS%203/3.07/>`_. (current at the time of writing although possibly subject to change) and extract the source files. Navigate to ``Contrib/ExDLL`` and copy ``pluginapi.h``, ``pluginapi.c`` and ``nsis_tchar.h`` to where header files for your Visual Studio project live. Add them to your project.
+
+7. You can use the following template to get started with your own plugin:
+
+.. code:: cpp
+
+  /* This Source Code Form is subject to the terms of the Mozilla Public
+  * License, v. 2.0. If a copy of the MPL was not distributed with this
+  * file, you can obtain one at http://mozilla.org/MPL/2.0/. */
+
+  // Put a brief description of your NSIS plugin here.
+
+  // Put your include statements here.
+  #include <sysheader>
+  #include "pluginapi.h" // This is taken from the NSIS plugin page
+  #include "myheader.h"
+
+  // A struct used for reading the stack passed in to the function
+  struct stack_t {
+    stack_t* next;
+    TCHAR text[MAX_PATH];
+  };
+
+  /**
+  *
+  *
+  * Put any additional functions you write here.
+  *
+  *
+  */
+
+  // I use popstringn and pushstringn from the NSIS pluginapi.h file.
+
+  // This is the function I want to call from within NSIS
+  extern "C" void __declspec(dllexport)
+  MyNSISFunction(HWND, int string_size, TCHAR* variables, stack_t** stacktop, void*) {
+    wchar_t getArg[MAX_PATH+1];
+    EXDLL_INIT();
+    bool rv = false;
+    int popRet = popstringn(getArg, MAX_PATH+1);
+    if (popRet == 0) {
+      rv = FunctionThatTakesAnArgument(getArg);
+    }
+    pushstring(rv ? L"1" : L"0");
+  }
+
+  BOOL APIENTRY
+  DllMain(HMODULE, DWORD, LPVOID) {
+    return TRUE;
+  }
+
+8. Modify ``$SRCDIR/toolkit/mozapps/installer/windows/nsis/makensis.mk`` as follows:
+
+.. code:: text
+
+  CUSTOM_NSIS_PLUGINS = \
+      ... \
+      MyPlugin.dll \
+      ... \
+      $(NULL)
+
+
+9. **NSIS only works with 32-bit plugins so ensure your Visual Studio build configuration is set to x86.** Compile your new plugin. ``exp`` and ``lib`` files will also be generated but they can safely be deleted.
+
+10. The plugin can now be called from within NSIS as follows:
+
+.. code:: text
+
+  MyPlugin::MyNSISFunc "$myNSISarg"
+
+.. note::
+
+  - You may need to run ``./mach clobber`` for your DLL to be recognized.
+  - You can compile your plugin in debug mode and step through it with a debugger by attaching to the installer/uninstall process.
+  - If libraries are needed, files in the ``$SRCDIR/mfbt/`` and ``$SRCDIR/toolkit/`` directories are usually okay although there may be exceptions.
+  - The best way to access headers is usually to simply copy them into the project given how disconnected this is from the rest of the build system.