diff --git a/.gitmodules b/.gitmodules
index f7807f5..0d72ced 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -5,3 +5,9 @@
 [submodule "external/LibraryLinkUtilities"]
 	path = external/LibraryLinkUtilities
 	url = https://github.com/WolframResearch/LibraryLinkUtilities
+[submodule "external/imgui"]
+	path = external/imgui
+	url = https://github.com/ocornut/imgui.git
+[submodule "external/glfw"]
+	path = external/glfw
+	url = https://github.com/glfw/glfw.git
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4952b53..83d5b6b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -4,7 +4,6 @@ cmake_minimum_required(VERSION 3.20)
 # Project
 # --------------------------------------------------
 project(wolfram-engine-wrapper-client LANGUAGES CXX)
-
 set(CMAKE_CXX_STANDARD 23)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
@@ -20,6 +19,63 @@ endif()
 add_subdirectory(external/spdlog)
 add_subdirectory(external/LibraryLinkUtilities)
 
+# --------------------------------------------------
+# External dependency: GLFW (cross-platform window/input)
+# --------------------------------------------------
+set(GLFW_BUILD_DOCS     OFF CACHE BOOL "" FORCE)
+set(GLFW_BUILD_TESTS    OFF CACHE BOOL "" FORCE)
+set(GLFW_BUILD_EXAMPLES OFF CACHE BOOL "" FORCE)
+set(GLFW_INSTALL        OFF CACHE BOOL "" FORCE)
+add_subdirectory(external/glfw)
+
+# --------------------------------------------------
+# External dependency: OpenGL
+# --------------------------------------------------
+find_package(OpenGL REQUIRED)
+
+# --------------------------------------------------
+# External dependency: Dear ImGui (no CMakeLists.txt
+# in upstream imgui — we build it manually here)
+# --------------------------------------------------
+set(IMGUI_DIR ${CMAKE_CURRENT_SOURCE_DIR}/external/imgui)
+
+add_library(imgui STATIC
+    ${IMGUI_DIR}/imgui.cpp
+    ${IMGUI_DIR}/imgui_demo.cpp
+    ${IMGUI_DIR}/imgui_draw.cpp
+    ${IMGUI_DIR}/imgui_tables.cpp
+    ${IMGUI_DIR}/imgui_widgets.cpp
+    # Cross-platform backends: GLFW + OpenGL3
+    ${IMGUI_DIR}/backends/imgui_impl_glfw.cpp
+    ${IMGUI_DIR}/backends/imgui_impl_opengl3.cpp
+)
+
+target_include_directories(imgui PUBLIC
+    ${IMGUI_DIR}
+    ${IMGUI_DIR}/backends
+)
+
+target_link_libraries(imgui PUBLIC
+    glfw
+    OpenGL::GL
+)
+
+# On macOS, GLFW needs Cocoa/IOKit/CoreVideo frameworks
+if(APPLE)
+    target_link_libraries(imgui PUBLIC
+        "-framework Cocoa"
+        "-framework IOKit"
+        "-framework CoreVideo"
+    )
+endif()
+
+# On Linux, link against dl and X11 (GLFW pulls these in but be explicit)
+if(UNIX AND NOT APPLE)
+    target_link_libraries(imgui PUBLIC
+        ${CMAKE_DL_LIBS}
+    )
+endif()
+
 # --------------------------------------------------
 # Executable
 # --------------------------------------------------
@@ -31,7 +87,6 @@ add_executable(${PROJECT_NAME} src/main.cpp)
 file(GLOB_RECURSE SRC_SUBDIRS LIST_DIRECTORIES true
     "${CMAKE_CURRENT_SOURCE_DIR}/src/*"
 )
-
 set(SRC_INCLUDES "")
 foreach(dir ${SRC_SUBDIRS})
     if(IS_DIRECTORY ${dir})
@@ -50,11 +105,9 @@ target_include_directories(${PROJECT_NAME} PRIVATE
 file(GLOB_RECURSE ALL_CPP
     "${CMAKE_CURRENT_SOURCE_DIR}/src/*.cpp"
 )
-
 list(REMOVE_ITEM ALL_CPP
     "${CMAKE_CURRENT_SOURCE_DIR}/src/main.cpp"
 )
-
 target_sources(${PROJECT_NAME} PRIVATE ${ALL_CPP})
 
 # --------------------------------------------------
@@ -63,6 +116,9 @@ target_sources(${PROJECT_NAME} PRIVATE ${ALL_CPP})
 target_link_libraries(${PROJECT_NAME} PRIVATE
     spdlog::spdlog
     LLU
+    imgui
+    OpenGL::GL
+    glfw
 )
 
 # --------------------------------------------------
@@ -77,3 +133,23 @@ if(CMAKE_CXX_COMPILER_ID MATCHES "Clang|GNU")
     )
 endif()
 
+# --------------------------------------------------
+# Windows-specific: subsystem and runtime
+# --------------------------------------------------
+if(WIN32)
+    # Use CONSOLE subsystem so stdout works; swap to WIN32 if you want
+    # a pure GUI app with no terminal (requires WinMain entry point)
+    set_target_properties(${PROJECT_NAME} PROPERTIES
+        WIN32_EXECUTABLE FALSE
+    )
+endif()
+
+# --------------------------------------------------
+# macOS-specific: bundle info (optional, comment out
+# if you don't want a .app bundle)
+# --------------------------------------------------
+if(APPLE)
+    set_target_properties(${PROJECT_NAME} PROPERTIES
+        MACOSX_BUNDLE FALSE  # set TRUE to produce a .app
+    )
+endif()
diff --git a/external/glfw b/external/glfw
new file mode 160000
index 0000000..7c9ea95
--- /dev/null
+++ b/external/glfw
@@ -0,0 +1 @@
+Subproject commit 7c9ea952338b792cb2f70d7c663e498725073797
diff --git a/external/imgui b/external/imgui
new file mode 160000
index 0000000..c234426
--- /dev/null
+++ b/external/imgui
@@ -0,0 +1 @@
+Subproject commit c234426f8985a30ac6c464f409ca75bedb38f85d