diff --git a/CMakeLists.txt b/CMakeLists.txt
index 463cd74c..40cfb44d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -9,8 +9,12 @@ option(APH_ENABLE_TSAN "Enable thread sanitizer" OFF)
 option(APH_ENABLE_ASAN "Enable address sanitizer" OFF)
 option(APH_ENABLE_MSAN "Enable memory sanitizer" OFF)
 
+SET(APH_WSI_BACKEND "Auto" CACHE STRING "WSI backend (possible values: Auto, GLFW, SDL2)")
+SET_PROPERTY(CACHE APH_WSI_BACKEND PROPERTY STRINGS Auto GLFW SDL2)
+
 set(APH_ROOT_DIR ${CMAKE_SOURCE_DIR})
 set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${APH_ROOT_DIR}/cmake")
+list(APPEND CMAKE_MODULE_PATH "${APH_ROOT_DIR}/cmake/modules")
 
 include(AphDefinitions)
 include(AphCompilerOptions)
diff --git a/cmake/AphExternal.cmake b/cmake/AphExternal.cmake
index 8e2a6c26..9a8544fa 100644
--- a/cmake/AphExternal.cmake
+++ b/cmake/AphExternal.cmake
@@ -30,7 +30,6 @@ option(BUILD_SHARED_LIBS "" OFF)
 add_subdirectory(${APH_EXTERNAL_DIR})
 add_subdirectory(${APH_EXTERNAL_DIR}/mimalloc EXCLUDE_FROM_ALL)
 add_subdirectory(${APH_EXTERNAL_DIR}/vma EXCLUDE_FROM_ALL)
-add_subdirectory(${APH_EXTERNAL_DIR}/glfw EXCLUDE_FROM_ALL)
 add_subdirectory(${APH_EXTERNAL_DIR}/volk EXCLUDE_FROM_ALL)
 add_subdirectory(${APH_EXTERNAL_DIR}/spirv-cross EXCLUDE_FROM_ALL)
 add_subdirectory(${APH_EXTERNAL_DIR}/imgui EXCLUDE_FROM_ALL)
@@ -42,3 +41,18 @@ add_subdirectory(${APH_EXTERNAL_DIR}/unordered_dense EXCLUDE_FROM_ALL)
 
 find_package(PkgConfig REQUIRED)
 pkg_check_modules(xcb REQUIRED IMPORTED_TARGET xcb)
+
+# wsi backend
+set(VALID_WSI_BACKENDS Auto GLFW SDL2)
+if(NOT (APH_WSI_BACKEND IN_LIST VALID_WSI_BACKENDS))
+    message(FATAL_ERROR "Wrong value passed for APH_WSI_BACKEND, use one of: Auto, GLFW, SDL2")
+endif()
+
+if(APH_WSI_BACKEND STREQUAL "Auto" OR APH_WSI_BACKEND STREQUAL "GLFW")
+    add_subdirectory(${APH_EXTERNAL_DIR}/glfw EXCLUDE_FROM_ALL)
+elseif(APH_WSI_BACKEND STREQUAL "SDL2")
+    find_package(SDL2)
+    if(NOT SDL2_FOUND)
+        message(FATAL_ERROR "SDL2 library not found!")
+    endif()
+endif()
diff --git a/cmake/modules/FindSDL2.cmake b/cmake/modules/FindSDL2.cmake
new file mode 100644
index 00000000..02c6bba0
--- /dev/null
+++ b/cmake/modules/FindSDL2.cmake
@@ -0,0 +1,172 @@
+# Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+# file Copyright.txt or https://cmake.org/licensing for details.
+
+# Locate SDL2 library
+# This module defines
+# SDL2_LIBRARY, the name of the library to link against
+# SDL2_FOUND, if false, do not try to link to SDL2
+# SDL2_INCLUDE_DIR, where to find SDL.h
+#
+# This module responds to the the flag:
+# SDL2_BUILDING_LIBRARY
+# If this is defined, then no SDL2_main will be linked in because
+# only applications need main().
+# Otherwise, it is assumed you are building an application and this
+# module will attempt to locate and set the the proper link flags
+# as part of the returned SDL2_LIBRARY variable.
+#
+# Don't forget to include SDL2main.h and SDL2main.m your project for the
+# OS X framework based version. (Other versions link to -lSDL2main which
+# this module will try to find on your behalf.) Also for OS X, this
+# module will automatically add the -framework Cocoa on your behalf.
+#
+#
+# Additional Note: If you see an empty SDL2_LIBRARY_TEMP in your configuration
+# and no SDL2_LIBRARY, it means CMake did not find your SDL2 library
+# (SDL2.dll, libsdl2.so, SDL2.framework, etc).
+# Set SDL2_LIBRARY_TEMP to point to your SDL2 library, and configure again.
+# Similarly, if you see an empty SDL2MAIN_LIBRARY, you should set this value
+# as appropriate. These values are used to generate the final SDL2_LIBRARY
+# variable, but when these values are unset, SDL2_LIBRARY does not get created.
+#
+#
+# $SDL2DIR is an environment variable that would
+# correspond to the ./configure --prefix=$SDL2DIR
+# used in building SDL2.
+# l.e.galup  9-20-02
+#
+# Modified by Eric Wing.
+# Added code to assist with automated building by using environmental variables
+# and providing a more controlled/consistent search behavior.
+# Added new modifications to recognize OS X frameworks and
+# additional Unix paths (FreeBSD, etc).
+# Also corrected the header search path to follow "proper" SDL2 guidelines.
+# Added a search for SDL2main which is needed by some platforms.
+# Added a search for threads which is needed by some platforms.
+# Added needed compile switches for MinGW.
+#
+# On OSX, this will prefer the Framework version (if found) over others.
+# People will have to manually change the cache values of
+# SDL2_LIBRARY to override this selection or set the CMake environment
+# CMAKE_INCLUDE_PATH to modify the search paths.
+#
+# Note that the header path has changed from SDL2/SDL.h to just SDL.h
+# This needed to change because "proper" SDL2 convention
+# is #include "SDL.h", not <SDL2/SDL.h>. This is done for portability
+# reasons because not all systems place things in SDL2/ (see FreeBSD).
+#
+# Ported by Johnny Patterson. This is a literal port for SDL2 of the FindSDL.cmake
+# module with the minor edit of changing "SDL" to "SDL2" where necessary. This
+# was not created for redistribution, and exists temporarily pending official
+# SDL2 CMake modules.
+
+FIND_PATH(SDL2_INCLUDE_DIR SDL.h
+  HINTS
+  $ENV{SDL2DIR}
+  PATH_SUFFIXES include/SDL2 include
+  PATHS
+  ~/Library/Frameworks
+  /Library/Frameworks
+  /usr/local/include/SDL2
+  /usr/include/SDL2
+  /sw # Fink
+  /opt/local # DarwinPorts
+  /opt/csw # Blastwave
+  /opt
+  /boot/system/develop/headers/SDL2 #Hiaku OS
+)
+#MESSAGE("SDL2_INCLUDE_DIR is ${SDL2_INCLUDE_DIR}")
+
+FIND_LIBRARY(SDL2_LIBRARY_TEMP
+  NAMES SDL2
+  HINTS
+  $ENV{SDL2DIR}
+  PATH_SUFFIXES lib64 lib
+  PATHS
+  /sw
+  /opt/local
+  /opt/csw
+  /opt
+  /system/lib #Hiaku OS
+)
+
+#MESSAGE("SDL2_LIBRARY_TEMP is ${SDL2_LIBRARY_TEMP}")
+
+IF(NOT SDL2_BUILDING_LIBRARY)
+  IF(NOT ${SDL2_INCLUDE_DIR} MATCHES ".framework")
+    # Non-OS X framework versions expect you to also dynamically link to
+    # SDL2main. This is mainly for Windows and OS X. Other (Unix) platforms
+    # seem to provide SDL2main for compatibility even though they don't
+    # necessarily need it.
+    FIND_LIBRARY(SDL2MAIN_LIBRARY
+      NAMES SDL2main
+      HINTS
+      $ENV{SDL2DIR}
+      PATH_SUFFIXES lib64 lib
+      PATHS
+      /sw
+      /opt/local
+      /opt/csw
+      /opt
+    )
+  ENDIF(NOT ${SDL2_INCLUDE_DIR} MATCHES ".framework")
+ENDIF(NOT SDL2_BUILDING_LIBRARY)
+
+# SDL2 may require threads on your system.
+# The Apple build may not need an explicit flag because one of the
+# frameworks may already provide it.
+# But for non-OSX systems, I will use the CMake Threads package.
+IF(NOT APPLE)
+  FIND_PACKAGE(Threads)
+ENDIF(NOT APPLE)
+
+# MinGW needs an additional library, mwindows
+# It's total link flags should look like -lmingw32 -lSDL2main -lSDL2 -lmwindows
+# (Actually on second look, I think it only needs one of the m* libraries.)
+IF(MINGW)
+  SET(MINGW32_LIBRARY mingw32 CACHE STRING "mwindows for MinGW")
+ENDIF(MINGW)
+
+SET(SDL2_FOUND "NO")
+IF(SDL2_LIBRARY_TEMP)
+  # For SDL2main
+  IF(NOT SDL2_BUILDING_LIBRARY)
+    IF(SDL2MAIN_LIBRARY)
+      SET(SDL2_LIBRARY_TEMP ${SDL2MAIN_LIBRARY} ${SDL2_LIBRARY_TEMP})
+    ENDIF(SDL2MAIN_LIBRARY)
+  ENDIF(NOT SDL2_BUILDING_LIBRARY)
+
+  # For OS X, SDL2 uses Cocoa as a backend so it must link to Cocoa.
+  # CMake doesn't display the -framework Cocoa string in the UI even
+  # though it actually is there if I modify a pre-used variable.
+  # I think it has something to do with the CACHE STRING.
+  # So I use a temporary variable until the end so I can set the
+  # "real" variable in one-shot.
+  IF(APPLE)
+    SET(SDL2_LIBRARY_TEMP ${SDL2_LIBRARY_TEMP} "-framework Cocoa")
+  ENDIF(APPLE)
+
+  # For threads, as mentioned Apple doesn't need this.
+  # In fact, there seems to be a problem if I used the Threads package
+  # and try using this line, so I'm just skipping it entirely for OS X.
+  IF(NOT APPLE)
+    SET(SDL2_LIBRARY_TEMP ${SDL2_LIBRARY_TEMP} ${CMAKE_THREAD_LIBS_INIT})
+  ENDIF(NOT APPLE)
+
+  # For MinGW library
+  IF(MINGW)
+    SET(SDL2_LIBRARY_TEMP ${MINGW32_LIBRARY} ${SDL2_LIBRARY_TEMP})
+  ENDIF(MINGW)
+
+  # Set the final string here so the GUI reflects the final state.
+  SET(SDL2_LIBRARY ${SDL2_LIBRARY_TEMP} CACHE STRING "Where the SDL2 Library can be found")
+  # Set the temp variable to INTERNAL so it is not seen in the CMake GUI
+  SET(SDL2_LIBRARY_TEMP "${SDL2_LIBRARY_TEMP}" CACHE INTERNAL "")
+
+  SET(SDL2_FOUND "YES")
+ENDIF(SDL2_LIBRARY_TEMP)
+
+INCLUDE(FindPackageHandleStandardArgs)
+
+FIND_PACKAGE_HANDLE_STANDARD_ARGS(SDL2
+                                  REQUIRED_VARS SDL2_LIBRARY SDL2_INCLUDE_DIR)
diff --git a/engine/wsi/CMakeLists.txt b/engine/wsi/CMakeLists.txt
index beee03a9..d94a69f1 100644
--- a/engine/wsi/CMakeLists.txt
+++ b/engine/wsi/CMakeLists.txt
@@ -1,5 +1,16 @@
-file(GLOB API_WSI_SRC ${APH_ENGINE_WSI_DIR}/*.cpp)
-add_library(wsi STATIC ${API_WSI_SRC})
+if(APH_WSI_BACKEND STREQUAL "Auto" OR APH_WSI_BACKEND STREQUAL "GLFW")
+    add_compile_definitions(WSI_USE_GLFW)
+    set(APH_WSI_SRC ${APH_ENGINE_WSI_DIR}/wsi_glfw.cpp)
+elseif(APH_WSI_BACKEND STREQUAL "SDL2")
+    if(NOT SDL2_FOUND)
+        message(FATAL_ERROR "SDL2 library not found!")
+    endif()
+    add_compile_definitions(WSI_USE_SDL2)
+    message(FATAL_ERROR "SDL2 is not supported.")
+    # set(APH_WSI_SRC ${APH_ENGINE_WSI_DIR}/wsi_sdl2.cpp)
+endif()
+
+add_library(wsi STATIC ${APH_WSI_SRC})
 aph_compiler_options(wsi)
 target_include_directories(wsi PRIVATE
   ${APH_ENGINE_DIR}