diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8680923..a564afe 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -4,6 +4,8 @@ project(Warthog
 	VERSION 0.5.0
 	LANGUAGES CXX C)
 
+set_property(GLOBAL PROPERTY WARTHOG_warthog-core ON)
+
 set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_STANDARD_REQUIRED TRUE)
 
@@ -12,7 +14,7 @@ option(WARTHOG_BMI "Enable support cpu BMI for WARTHOG_INTRIN_HAS(BMI)" OFF)
 option(WARTHOG_BMI2 "Enable support cpu BMI2 for WARTHOG_INTRIN_HAS(BMI2), use for Zen 3+" OFF)
 option(WARTHOG_INTRIN_ALL "Enable march=native and support x86 intrinsics if able (based on system), supersedes all manual instruction sets" OFF)
 
-include(cmake/submodule.cmake)
+include(cmake/warthog.cmake)
 
 add_library(warthog_compile INTERFACE)
 add_library(warthog::compile ALIAS warthog_compile)
diff --git a/README.md b/README.md
index 453f0b5..0179bcc 100644
--- a/README.md
+++ b/README.md
@@ -22,25 +22,104 @@ Requires `warthog-core` as a dependency.
 
 # Using warthog
 
-Warthog dependencies are setup using git-submodules, use commands below are used to initialise and update respectively:
-    git submodule init
-    git submodule update
+It is recommended to use warthog not as a fork, but included in an external repo.
+This setup support FetchContent, git submodule and git subtree.
 
-All dependencies should be placed in `/extern`.
-If not project forked, we suggest setting the project up as below:
+## CMake
+
+Setup a basic project using the following the commands:
+
+    git init
+    git remote add warthog-core https://github.com/ShortestPathLab/warthog-core.git
+    git fetch warthog-core
+    git checkout warthog-core/main cmake/warthog.cmake
+
+Example `CMakeLists.txt`:
 
-1. Copy `/cmake/submodule.cmake` to your repo
-2. Submodule or subtree all your warthog dependencies and their dependencies into `/extern`
-3. In `/CMakeLists.txt`, setup as below:
 ```
-include(cmake/submodule.cmake)
-warthog_submodule(warthog-[module]) # repeat for each [module]
+cmake_minimum_required(VERSION 3.13)
+
+project(App
+	VERSION 0.0.1
+	LANGUAGES CXX C)
+
+set(CMAKE_CXX_STANDARD 20)
+set(CMAKE_CXX_STANDARD_REQUIRED TRUE)
+
+# warthog modules
+include(cmake/warthog.cmake)
+
+warthog_module_declare(warthog-core v0.5.0) # is optional, remove for default of main
+warthog_module(warthog-core)
+
+add_executable(app main.cpp)
+target_link_libraries(app PUBLIC warthog::core)
 ```
 
-With (2) we flatten dependencies to top-level project.
-With (3) `warthog_submodule` will add `add_subdirectoy` if your CMake is the top level config.
+## Submodule
+
+Commands for adding a module as a submodules for each repo are found below:
+
+    git submodule add https://github.com/ShortestPathLab/warthog-core.git extern/warthog-core
+    git submodule add https://github.com/ShortestPathLab/warthog-jps.git extern/warthog-jps
+
+To update the version of warthog, for warthog module `$module`:
+
+    cd extern/$module
+    git fetch
+    git checkout|git switch
+    cd ..
+    git add $module
+
+This will update the submodule to the checkout commit.
+Initialise or update the submodule on other clones with
+the following commands:
+
+    git submodule init # after clone
+    git submodule update # after pull
 
-An informal project not designed to be a dependency does not require this, and can just `add_subdirectory` to all dependencies.
+## Subtree
+
+Subtree will make the module a part of your repo, allowing
+for local editing without forking.
+
+The setup for each module:
+
+    git subtree -P extern/warthog-core add https://github.com/ShortestPathLab/warthog-core.git main|branch|commit --squash
+    git subtree -P extern/warthog-jps add https://github.com/ShortestPathLab/warthog-jps.git main|branch|commit --squash
+
+The update commands:
+
+    git subtree -P extern/warthog-core pull https://github.com/ShortestPathLab/warthog-core.git main|branch|commit --squash
+    git subtree -P extern/warthog-jps pull https://github.com/ShortestPathLab/warthog-jps.git main|branch|commit --squash
+
+## Advance Module Details
+
+File `/cmake/warthog.cmake` from warthog core should be copied to user repo and `include` in CMake.
+Calling `warthog_submodule(warthog-core)` will then add `warthog-core` to your CMake in the following order:
+1. `add_subdirectory(/extern/warthog-core)` if `/extern/warthog-core/CMakeLists.txt` exists (submodule/subtree)
+2. `FetchContent_Declare` then `FetchContent_MakeAvailable(warthog-core)` otherwise
+3. Error if cannot find `warthog-core` content
+
+The `warthog_module` call only adds a module once, the following calls will be ignored.
+The submodule/subtree version only works if called in the top level project by default;
+if this method is preferred, then it should be added to the top level `/extern/`, can be overridden
+with code `warthog_module(warthog-core ON)`.
+
+Declare of warthog-core can be done using the following code:
+```
+warthog_module_declare(warthog-core [main|branch|tag|commit])
+```
+or:
+```
+FetchContent_Declare(warthog-core
+	GIT_REPOSITORY https://github.com/ShortestPathLab/warthog-core.git
+	GIT_TAG [main|branch|tag|commit])
+```
+This will declare what warthog-core version to fetched.
+The `warthog_module_declare` version makes it simple, although it only supports known warthog libraries.
+The optional second parameter sets the version to pull, by default is `main` branch.
+This system only support warthog 0.5 or greater.
 
 # Resources
 
diff --git a/cmake/submodule.cmake b/cmake/submodule.cmake
deleted file mode 100644
index da47f29..0000000
--- a/cmake/submodule.cmake
+++ /dev/null
@@ -1,35 +0,0 @@
-cmake_minimum_required(VERSION 3.13)
-
-# include this file to check submodule include
-
-set(WARTHOG_SUBMODULE_ROOT_ONLY ON CACHE BOOL "add submodule if present only allowed for root project")
-
-function(warthog_top_level)
-set(_is_top OFF)
-if(${CMAKE_VERSION} VERSION_GREATER_EQUAL 3.21)
-	if(${PROJECT_IS_TOP_LEVEL})
-		set(_is_top ON)
-	endif()
-else()
-	if(${CMAKE_SOURCE_DIR} STREQUAL ${PROJECT_SOURCE_DIR})
-		set(_is_top ON)
-	endif()
-endif()
-set(_is_top ${_is_top} PARENT_SCOPE)
-endfunction()
-
-function(warthog_submodule dirname)
-set(_is_top OFF)
-if(NOT ${WARTHOG_SUBMODULE_ROOT_ONLY})
-	set(_is_top ON)
-else()
-	warthog_top_level()
-endif()
-if(${_is_top})
-	if(NOT EXISTS "${PROJECT_SOURCE_DIR}/extern/${dirname}/.git")
-		message(SEND_ERROR "Failed to find submodule ${dirname}")
-	else()
-		add_subdirectory("${PROJECT_SOURCE_DIR}/extern/${dirname}" EXCLUDE_FROM_ALL)
-	endif()
-endif()
-endfunction()
diff --git a/cmake/warthog.cmake b/cmake/warthog.cmake
new file mode 100644
index 0000000..635f050
--- /dev/null
+++ b/cmake/warthog.cmake
@@ -0,0 +1,76 @@
+cmake_minimum_required(VERSION 3.13)
+
+# include this file to check submodule include
+
+# set here as only
+set(warthog_https_warthog-core "https://github.com/ShortestPathLab/warthog-core.git" CACHE INTERNAL "")
+set(warthog_https_warthog-jps "https://github.com/ShortestPathLab/warthog-jps.git" CACHE INTERNAL "")
+
+if(COMMAND warthog_module)
+	return() # do not redefine
+endif()
+
+include(FetchContent)
+
+set(WARTHOG_MODULE_ROOT_ONLY ON CACHE BOOL "add submodule if present only allowed for root project")
+
+function(warthog_top_level)
+set(_is_top OFF)
+if(${CMAKE_VERSION} VERSION_GREATER_EQUAL 3.21)
+	if(${PROJECT_IS_TOP_LEVEL})
+		set(_is_top ON)
+	endif()
+else()
+	if(${CMAKE_SOURCE_DIR} STREQUAL ${PROJECT_SOURCE_DIR})
+		set(_is_top ON)
+	endif()
+endif()
+set(_warthog_is_top ${_is_top} PARENT_SCOPE)
+endfunction()
+
+# warthog_module module [override_top]
+# adds a module to warthog
+# has checks to insure module is only added once
+# if called from the top level project (or optional variable override_top is true)
+# then if extern/${module}/CMakeLists.txt exists, adds that version instead
+#    intended for use with git module/subtree.
+# otherwise, fetchcontent ${module} is made available
+# user must add FetchContent_Declare
+function(warthog_module module)
+get_property(_module_added GLOBAL PROPERTY WARTHOG_${module} SET)
+if(${_module_added}) # module already added
+	return()
+endif()
+if((${ARGC} GREATER 1) AND (${ARGV1}))
+	set(is_top_level ON)
+else()
+	warthog_top_level()
+	set(is_top_level ${_warthog_is_top})
+endif()
+if(${is_top_level})
+	if(EXISTS "${PROJECT_SOURCE_DIR}/extern/${module}/CMakeLists.txt")
+		# module or subtree, include and exit
+		add_subdirectory("${PROJECT_SOURCE_DIR}/extern/${module}")
+		set_property(GLOBAL PROPERTY WARTHOG_${module} ON)
+		return()
+	endif()
+endif()
+# failed to add module, fetch if able
+warthog_module_declare(${module})
+FetchContent_MakeAvailable(${module})
+set_property(GLOBAL PROPERTY WARTHOG_${module} ON)
+endfunction()
+
+function(warthog_module_declare module)
+if(NOT DEFINED warthog_https_${module})
+	return()
+endif()
+if((${ARGC} GREATER 1))
+	set(git_tag ${ARGV1})
+else()
+	set(git_tag "main")
+endif()
+FetchContent_Declare(${module}
+	GIT_REPOSITORY ${warthog_https_${module}}
+	GIT_TAG ${git_tag})
+endfunction()