diff --git a/CMakeLists.txt b/CMakeLists.txt
index 46685cc..ee82fe9 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -85,3 +85,17 @@ option(
 if(WITH_PGIS)
   add_subdirectory(pgis)
 endif()
+
+# If set to on, CMake looks for installed nlohmann::json
+option(
+  METACG_USE_EXTERNAL_JSON
+  "On or off"
+  OFF
+)
+
+# if set to on, CMake looks for installed spdlog
+option(
+  METACG_USE_EXTERNAL_SPDLOG
+  "On or off"
+  OFF
+)
diff --git a/cmake/ToolchainOptions.cmake b/cmake/ToolchainOptions.cmake
index e30e72c..d8895da 100644
--- a/cmake/ToolchainOptions.cmake
+++ b/cmake/ToolchainOptions.cmake
@@ -23,6 +23,7 @@ find_path(EXTRAP_INCLUDE extrap)
 
 include(json)
 include(cxxopts)
+include(spdlog)
 
 # External dependencies
 function(add_clang target)
@@ -51,10 +52,6 @@ function(add_extrap target)
   target_link_libraries(${target} extrap)
 endfunction()
 
-function(add_spdlog_libraries target)
-  target_link_libraries(${target} spdlog::spdlog)
-endfunction()
-
 function(add_cube target)
   target_include_directories(${target} SYSTEM PUBLIC ${CUBE_INCLUDE})
   target_link_directories(
@@ -209,39 +206,18 @@ if(CMAKE_VERSION
 )
   include_directories("${gtest_SOURCE_DIR}/include")
 endif()
-
-# Download and unpack spdlog at configure time
-configure_file(cmake/spdlog.cmake.in spdlog-download/CMakeLists.txt)
-execute_process(
-  COMMAND ${CMAKE_COMMAND} -G "${CMAKE_GENERATOR}" .
-  RESULT_VARIABLE spdresult
-  WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/spdlog-download
-)
-if(spdresult)
-  message(FATAL_ERROR "CMake step for spdlog failed: ${spdresult}")
-endif()
-execute_process(
-  COMMAND ${CMAKE_COMMAND} --build .
-  RESULT_VARIABLE spdresult
-  WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/spdlog-download
-)
-if(spdresult)
-  message(FATAL_ERROR "Build step for spdlog failed: ${spdresult}")
-endif()
-
-# Prevent overriding the parent project's compiler/linker settings on Windows
-set(spdlog_force_shared_crt
-    ON
-    CACHE BOOL
-          ""
-          FORCE
-)
-
-# Add spdlog directly to our build.
-add_subdirectory(
-  ${CMAKE_CURRENT_BINARY_DIR}/spdlog-src
-  ${CMAKE_CURRENT_BINARY_DIR}/spdlog-build
-  EXCLUDE_FROM_ALL
-)
-
-install(TARGETS spdlog DESTINATION lib)
+#
+# Download and unpack spdlog at configure time configure_file(cmake/spdlog.cmake spdlog-download/CMakeLists.txt)
+# execute_process( COMMAND ${CMAKE_COMMAND} -G "${CMAKE_GENERATOR}" . RESULT_VARIABLE spdresult WORKING_DIRECTORY
+# ${CMAKE_CURRENT_BINARY_DIR}/spdlog-download ) if(spdresult) message(FATAL_ERROR "CMake step for spdlog failed:
+# ${spdresult}") endif() execute_process( COMMAND ${CMAKE_COMMAND} --build . RESULT_VARIABLE spdresult WORKING_DIRECTORY
+# ${CMAKE_CURRENT_BINARY_DIR}/spdlog-download ) if(spdresult) message(FATAL_ERROR "Build step for spdlog failed:
+# ${spdresult}") endif()
+#
+# Prevent overriding the parent project's compiler/linker settings on Windows set(spdlog_force_shared_crt ON CACHE BOOL
+# "" FORCE )
+#
+# Add spdlog directly to our build. add_subdirectory( ${CMAKE_CURRENT_BINARY_DIR}/spdlog-src
+# ${CMAKE_CURRENT_BINARY_DIR}/spdlog-build EXCLUDE_FROM_ALL )
+#
+# install(TARGETS spdlog DESTINATION lib)
diff --git a/cmake/json.cmake b/cmake/json.cmake
index 7078f5c..e7c84da 100644
--- a/cmake/json.cmake
+++ b/cmake/json.cmake
@@ -1,31 +1,23 @@
-include(ExternalProject)
+include(FetchContent)
 
-if(DEFINED JSON_INCLUDE)
-  message("JSON_INCLUDE predefined: ${JSON_INCLUDE}")
+if(METACG_USE_EXTERNAL_JSON)
+  message("Using externally found json library")
+  # Taken from https://cmake.org/cmake/help/v3.16/command/find_package.html#version-selection Should enable to use the
+  # highest available version number, should the package provide sorting
+  set(CMAKE_FIND_PACKAGE_SORT_ORDER NATURAL)
+  set(CMAKE_FIND_PACKAGE_SORT_DIRECTION DEC)
+  find_package(
+    nlohmann_json
+    3.10
+    REQUIRED
+  )
 else()
-  find_path(JSON_LIBRARY NAMES json)
-  if(JSON_LIBRARY)
-    set(JSON_INCLUDE ${JSON_LIBRARY}/json/single_include)
-    message("JSON found in ${JSON_INCLUDE}")
-  else()
-    message("JSON library not found, download into extern during make")
-    ExternalProject_Add(
-      json
-      SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/extern/json
-      GIT_REPOSITORY "https://github.com/nlohmann/json.git"
-      GIT_TAG master
-      CONFIGURE_COMMAND ""
-      BUILD_COMMAND ""
-      INSTALL_COMMAND ""
-      TEST_COMMAND ""
-      GIT_SHALLOW true
-    )
-    set(JSON_INCLUDE ${CMAKE_CURRENT_SOURCE_DIR}/extern/json/single_include)
-  endif()
+  message("Using fetched release version of json library")
+
+  FetchContent_Declare(json URL https://github.com/nlohmann/json/releases/download/v3.10.5/json.tar.xz)
+  FetchContent_MakeAvailable(json)
 endif()
 
 function(add_json target)
-  add_dependencies(${target} json)
-
-  target_include_directories(${target} SYSTEM PUBLIC ${JSON_INCLUDE})
+  target_link_libraries(${target} nlohmann_json::nlohmann_json)
 endfunction()
diff --git a/cmake/spdlog.cmake b/cmake/spdlog.cmake
new file mode 100644
index 0000000..424785a
--- /dev/null
+++ b/cmake/spdlog.cmake
@@ -0,0 +1,26 @@
+include(FetchContent)
+
+if(METACG_USE_EXTERNAL_SPDLOG)
+  message("Using externally found spdlog library")
+  find_package(
+    spdlog
+    1.8.2
+    REQUIRED
+  )
+else()
+  message("Using fetched release version of spdlog library")
+
+  FetchContent_Declare(spdlog URL https://github.com/gabime/spdlog/archive/refs/tags/v1.8.2.tar.gz)
+  FetchContent_MakeAvailable(spdlog)
+
+  # Only install when spdlog is desired as automatically downloaded library
+  install(
+    TARGETS spdlog
+    LIBRARY DESTINATION lib
+    ARCHIVE DESTINATION lib
+  )
+endif()
+
+function(add_spdlog_libraries target)
+  target_link_libraries(${target} spdlog::spdlog)
+endfunction()
diff --git a/cmake/spdlog.cmake.in b/cmake/spdlog.cmake.in
deleted file mode 100644
index 60cc3ea..0000000
--- a/cmake/spdlog.cmake.in
+++ /dev/null
@@ -1,19 +0,0 @@
-cmake_minimum_required(VERSION 3.2)
-
-project(spdlog-download NONE)
-
-include(ExternalProject)
-# cmake-format: off
-ExternalProject_Add(
-  spdlog
-  GIT_REPOSITORY      https://github.com/gabime/spdlog.git
-  GIT_TAG             v1.8.2
-  SOURCE_DIR          "${CMAKE_CURRENT_BINARY_DIR}/spdlog-src"
-  BINARY_DIR          "${CMAKE_CURRENT_BINARY_DIR}/spdlog-build"
-  CONFIGURE_COMMAND   ""
-  BUILD_COMMAND       ""
-  INSTALL_COMMAND     ""
-  TEST_COMMAND        ""
-  CMAKE_ARGS          -DSPDLOG_BUILD_SHARED=ON
-)
-# cmake-format: on