diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 86105bfb..d493bdab 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -101,6 +101,13 @@ test_guidelines:
     - docker run -e CCACHE_DIR=/ccache -v /mnt/ccache:/ccache netgen_${CI_BUILD_REF_NAME}:${UBUNTU_VERSION} bash /root/src/netgen/tests/build_guidelines.sh
   when: always
 
+# check if it compiles without spdlog
+test_noSpdlog:
+  <<: *ubuntu
+  stage: test
+  script:
+    - docker run -e CCACHE_DIR=/ccache -v /mnt/ccache:/ccache netgen_${CI_BUILD_REF_NAME}:${UBUNTU_VERSION} bash /root/src/netgen/tests/build_nospdlog.sh
+
 cleanup_ubuntu:
   stage: cleanup
   tags:
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 14931c4d..5d2e6a9f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -19,6 +19,8 @@ option( USE_CCACHE       "use ccache")
 option( USE_INTERNAL_TCL "Compile tcl files into the code and don't install them" ON)
 option( ENABLE_UNIT_TESTS "Enable Catch unit tests")
 option( ENABLE_CPP_CORE_GUIDELINES_CHECK "Enable cpp core guideline checks on ngcore" OFF)
+option( USE_SPDLOG "Enable spd log logging" ON)
+option( DEBUG_LOG "Enable more debug output (may increase computation time) - only works with USE_SPDLOG=ON" OFF)
 
 option( USE_SUPERBUILD       "use ccache" ON)
 
@@ -258,6 +260,7 @@ endif (USE_GUI)
 
 #######################################################################
 if (USE_PYTHON)
+    add_subdirectory(external_dependencies/pybind11)
     add_definitions(-DNG_PYTHON)
     find_path(PYBIND_INCLUDE_DIR pybind11/pybind11.h HINTS ${PYTHON_INCLUDE_DIR})
     if( PYBIND_INCLUDE_DIR )
@@ -350,6 +353,11 @@ endif(ENABLE_UNIT_TESTS)
 
 #######################################################################
 
+if(USE_SPDLOG)
+  include(${CMAKE_CURRENT_SOURCE_DIR}/cmake/external_projects/spdlog.cmake)
+  include_directories(${SPDLOG_INCLUDE_DIR})
+endif(USE_SPDLOG)
+
 if(ENABLE_CPP_CORE_GUIDELINES_CHECK)
   find_program(
     CLANG_TIDY_EXE
diff --git a/cmake/SuperBuild.cmake b/cmake/SuperBuild.cmake
index 36ea3fcb..6e7fabd7 100644
--- a/cmake/SuperBuild.cmake
+++ b/cmake/SuperBuild.cmake
@@ -142,6 +142,8 @@ set_vars( NETGEN_CMAKE_ARGS
   CMAKE_INSTALL_PREFIX
   ENABLE_UNIT_TESTS
   ENABLE_CPP_CORE_GUIDELINES_CHECK
+  USE_SPDLOG
+  DEBUG_LOG
   )
 
 # propagate all variables set on the command line using cmake -DFOO=BAR
diff --git a/cmake/external_projects/spdlog.cmake b/cmake/external_projects/spdlog.cmake
new file mode 100644
index 00000000..d932ebef
--- /dev/null
+++ b/cmake/external_projects/spdlog.cmake
@@ -0,0 +1,18 @@
+include(ExternalProject)
+find_program(GIT_EXECUTABLE git)
+
+ExternalProject_Add(
+  project_spdlog
+  PREFIX ${CMAKE_BINARY_DIR}/spdlog
+  GIT_REPOSITORY https://github.com/gabime/spdlog.git
+  GIT_TAG v1.2.1
+  TIMEOUT 01
+  UPDATE_COMMAND ""
+  CONFIGURE_COMMAND ""
+  BUILD_COMMAND ""
+  INSTALL_COMMAND ""
+  LOG_DOWNLOAD ON
+  )
+
+ExternalProject_Get_Property(project_spdlog source_dir)
+set(SPDLOG_INCLUDE_DIR ${source_dir}/include)
diff --git a/libsrc/core/CMakeLists.txt b/libsrc/core/CMakeLists.txt
index 92f2e8b7..16cec927 100644
--- a/libsrc/core/CMakeLists.txt
+++ b/libsrc/core/CMakeLists.txt
@@ -1,16 +1,41 @@
-add_library(ngcore SHARED archive.cpp)
 
-target_compile_definitions(ngcore PRIVATE -DNGCORE_EXPORTS)
+add_library(ngcore SHARED archive.cpp logging.cpp)
+
+target_compile_definitions(ngcore PRIVATE NGCORE_EXPORTS)
+if(NOT WIN32)
+  target_compile_options(ngcore PRIVATE -fvisibility=hidden)
+endif(NOT WIN32)
+
+if(USE_SPDLOG)
+  include_directories(${SPDLOG_INCLUDE_DIR})
+  install(DIRECTORY ${SPDLOG_INCLUDE_DIR}
+    DESTINATION ${NG_INSTALL_DIR_INCLUDE}
+    )
+  add_dependencies(ngcore project_spdlog)
+  target_compile_definitions(ngcore PUBLIC NETGEN_USE_SPDLOG)
+  if(DEBUG_LOG)
+    target_compile_definitions(ngcore PUBLIC NETGEN_LOG_DEBUG)
+  endif(DEBUG_LOG)
+endif(USE_SPDLOG)
 
 install(TARGETS ngcore DESTINATION ${NG_INSTALL_DIR} COMPONENT netgen)
 
 if(USE_PYTHON)
+  target_compile_definitions(ngcore PUBLIC NETGEN_PYTHON)
   target_include_directories(ngcore PUBLIC ${PYTHON_INCLUDE_DIRS})
 endif(USE_PYTHON)
 
-install(FILES ngcore.hpp archive.hpp type_traits.hpp version.hpp ngcore_api.hpp
+install(FILES ngcore.hpp archive.hpp type_traits.hpp version.hpp ngcore_api.hpp logging.hpp
   DESTINATION ${NG_INSTALL_DIR_INCLUDE}/core COMPONENT netgen_devel)
 
 if(ENABLE_CPP_CORE_GUIDELINES_CHECK)
   set_target_properties(ngcore PROPERTIES CXX_CLANG_TIDY "${DO_CLANG_TIDY}")
 endif(ENABLE_CPP_CORE_GUIDELINES_CHECK)
+
+if(USE_PYTHON)
+  pybind11_add_module(pyngcore SHARED python_ngcore.cpp)
+  target_link_libraries(pyngcore PUBLIC ngcore)
+  set_target_properties(pyngcore PROPERTIES INSTALL_RPATH "${NG_RPATH_TOKEN}/${NETGEN_PYTHON_RPATH}")
+  install(TARGETS pyngcore DESTINATION ${NG_INSTALL_DIR_PYTHON} COMPONENT netgen)
+endif(USE_PYTHON)
+
diff --git a/libsrc/core/archive.hpp b/libsrc/core/archive.hpp
index fd2ee275..aa6537d2 100644
--- a/libsrc/core/archive.hpp
+++ b/libsrc/core/archive.hpp
@@ -3,24 +3,25 @@
 
 #include <complex>              // for complex
 #include <cstring>              // for size_t, strlen
-#include <fstream>              // for operator<<, ifstream, ofstream, basic...
+#include <fstream>              // for ifstream, ofstream
 #include <functional>           // for function
-#include <map>                  // for map, _Rb_tree_iterator
-#include <memory>               // for __shared_ptr_access, __shared_ptr_acc...
+#include <map>                  // for map
+#include <memory>               // for shared_ptr
 #include <stdexcept>            // for runtime_error
-#include <string>               // for string, operator+
+#include <string>               // for string
 #include <type_traits>          // for declval, enable_if, false_type, is_co...
 #include <typeinfo>             // for type_info
 #include <utility>              // for move, swap, pair
 #include <vector>               // for vector
 
+#include "logging.hpp"          // for logger
 #include "ngcore_api.hpp"       // for NGCORE_API, unlikely
 #include "type_traits.hpp"      // for all_of_tmpl
 #include "version.hpp"          // for VersionInfo
 
-#ifdef NG_PYTHON
+#ifdef NETGEN_PYTHON
 #include <pybind11/pybind11.h>
-#endif // NG_PYTHON
+#endif // NETGEN_PYTHON
 
 namespace ngcore
 {
@@ -104,20 +105,28 @@ namespace ngcore
     std::vector<void*> nr2ptr;
   protected:
     bool shallow_to_python = false;
+    // version map is only used in InArchives
+    std::map<std::string, VersionInfo> version_map;
+    std::shared_ptr<spdlog::logger> logger;
   public:
     Archive() = delete;
     Archive(const Archive&) = delete;
     Archive(Archive&&) = delete;
-    Archive (bool ais_output) :
-      is_output(ais_output), shared_ptr_count(0), ptr_count(0) { ; }
+    Archive (bool ais_output) : is_output(ais_output), shared_ptr_count(0),
+    ptr_count(0), logger(GetLogger("Archive")) { ; }
 
     virtual ~Archive() { ; }
 
+    // If the object is pickled, all shallow archived objects will be pickled as a list,
+    // instead of written as a binary archive. This allows pickle to serialize every object only
+    // once and put them together correctly afterwards. Therefore all objects that may live in
+    // Python should be archived using this Shallow function. If Shallow is called from C++ code
+    // it archives the object normally.
     template<typename T>
     Archive& Shallow(T& val)
     {
       static_assert(detail::is_any_pointer<T>, "ShallowArchive must be given pointer type!");
-#ifdef NG_PYTHON
+#ifdef NETGEN_PYTHON
       if(shallow_to_python)
         {
           if(is_output)
@@ -126,17 +135,17 @@ namespace ngcore
             val = pybind11::cast<T>(ShallowInPython());
         }
       else
-#endif // NG_PYTHON
+#endif // NETGEN_PYTHON
         *this & val;
       return *this;
     }
 
-#ifdef NG_PYTHON
-    virtual void ShallowOutPython(pybind11::object /*unused*/) // NOLINT (copy by val is ok for this virt func)
+#ifdef NETGEN_PYTHON
+    virtual void ShallowOutPython(const pybind11::object& /*unused*/)
     { throw std::runtime_error("Should not get in ShallowToPython base class implementation!"); }
     virtual pybind11::object ShallowInPython()
     { throw std::runtime_error("Should not get in ShallowFromPython base class implementation!"); }
-#endif // NG_PYTHON
+#endif // NETGEN_PYTHON
 
     Archive& operator=(const Archive&) = delete;
     Archive& operator=(Archive&&) = delete;
@@ -261,28 +270,39 @@ namespace ngcore
     {
       if(Output())
         {
+          NETGEN_DEBUG_LOG(logger, "Store shared ptr of type " + Demangle(typeid(T).name()));
           // save -2 for nullptr
           if(!ptr)
-            return (*this) << -2;
+            {
+              NETGEN_DEBUG_LOG(logger, "Storing nullptr");
+              return (*this) << -2;
+            }
 
           void* reg_ptr = ptr.get();
           bool neededDowncast = false;
           // Downcasting is only possible for our registered classes
           if(typeid(T) != typeid(*ptr))
             {
+              NETGEN_DEBUG_LOG(logger, "Typids are different: " + Demangle(typeid(T).name()) + " vs. " +
+                               Demangle(typeid(*ptr).name()));
               if(!IsRegistered(Demangle(typeid(*ptr).name())))
                   throw std::runtime_error(std::string("Archive error: Polymorphic type ")
                                            + Demangle(typeid(*ptr).name())
                                            + " not registered for archive");
               reg_ptr = GetArchiveRegister(Demangle(typeid(*ptr).name())).downcaster(typeid(T), ptr.get());
               // if there was a true downcast we have to store more information
-              if(reg_ptr != static_cast<void*>(ptr.get()) )
+              if(reg_ptr != static_cast<void*>(ptr.get()))
+                {
+                  NETGEN_DEBUG_LOG(logger, "Multiple/Virtual inheritance involved, need to cast pointer");
                   neededDowncast = true;
+                }
             }
           auto pos = shared_ptr2nr.find(reg_ptr);
           // if not found store -1 and the pointer
           if(pos == shared_ptr2nr.end())
             {
+              NETGEN_DEBUG_LOG(logger, "Didn't find the shared_ptr, create new registry entry at " +
+                               std::to_string(shared_ptr_count));
               auto p = ptr.get();
               (*this) << -1;
               (*this) & neededDowncast & p;
@@ -293,23 +313,27 @@ namespace ngcore
               return *this;
             }
           // if found store the position and if it has to be downcasted and how
+          NETGEN_DEBUG_LOG(logger, "Found shared_ptr at position " + std::to_string(pos->second));
           (*this) << pos->second << neededDowncast;
           if(neededDowncast)
             (*this) << Demangle(typeid(*ptr).name());
         }
       else // Input
         {
+          NETGEN_DEBUG_LOG(logger, "Reading shared_ptr of type " + Demangle(typeid(T).name()));
           int nr;
           (*this) & nr;
           // -2 restores a nullptr
           if(nr == -2)
             {
+              NETGEN_DEBUG_LOG(logger, "Reading a nullptr");
               ptr = nullptr;
               return *this;
             }
           // -1 restores a new shared ptr by restoring the inner pointer and creating a shared_ptr to it
           if (nr == -1)
             {
+              NETGEN_DEBUG_LOG(logger, "Createing new shared_ptr");
               T* p = nullptr;
               bool neededDowncast;
               (*this) & neededDowncast & p;
@@ -317,6 +341,7 @@ namespace ngcore
               // if we did downcast we need to store a shared_ptr<void> to the true object
               if(neededDowncast)
                 {
+                  NETGEN_DEBUG_LOG(logger, "Shared pointer needed downcasting");
                   std::string name;
                   (*this) & name;
                   auto info = GetArchiveRegister(name);
@@ -327,15 +352,20 @@ namespace ngcore
                                                                                 ptr.get())));
                 }
               else
-                nr2shared_ptr.push_back(ptr);
+                {
+                  NETGEN_DEBUG_LOG(logger, "Shared pointer didn't need downcasting");
+                  nr2shared_ptr.push_back(ptr);
+                }
             }
           else
             {
+              NETGEN_DEBUG_LOG(logger, "Reading already existing pointer at entry " + std::to_string(nr));
               auto other = nr2shared_ptr[nr];
               bool neededDowncast;
               (*this) & neededDowncast;
               if(neededDowncast)
                 {
+                  NETGEN_DEBUG_LOG(logger, "Shared pointer needed pointer downcast");
                   // if there was a downcast we can expect the class to be registered (since archiving
                   // wouldn't have worked else)
                   std::string name;
@@ -348,7 +378,10 @@ namespace ngcore
                                                                                other.get())));
                 }
               else
-                ptr = std::static_pointer_cast<T>(other);
+                {
+                  NETGEN_DEBUG_LOG(logger, "Shared pointer didn't need pointer casts");
+                  ptr = std::static_pointer_cast<T>(other);
+                }
             }
         }
       return *this;
@@ -360,26 +393,39 @@ namespace ngcore
     {
       if (Output())
         {
+          NETGEN_DEBUG_LOG(logger, "Store pointer of type " + Demangle(typeid(T).name()));
           // if the pointer is null store -2
           if (!p)
-            return (*this) << -2;
+            {
+              NETGEN_DEBUG_LOG(logger, "Storing nullptr");
+              return (*this) << -2;
+            }
           auto reg_ptr = static_cast<void*>(p);
           if(typeid(T) != typeid(*p))
             {
+              NETGEN_DEBUG_LOG(logger, "Typeids are different: " + Demangle(typeid(T).name()) + " vs. " +
+                               Demangle(typeid(*p).name()));
               if(!IsRegistered(Demangle(typeid(*p).name())))
                 throw std::runtime_error(std::string("Archive error: Polymorphic type ")
                                          + Demangle(typeid(*p).name())
                                          + " not registered for archive");
               reg_ptr = GetArchiveRegister(Demangle(typeid(*p).name())).downcaster(typeid(T), static_cast<void*>(p));
+              if(reg_ptr != static_cast<void*>(p))
+                {
+                  NETGEN_DEBUG_LOG(logger, "Multiple/Virtual inheritance involved, need to cast pointer");
+                }
             }
           auto pos = ptr2nr.find(reg_ptr);
           // if the pointer is not found in the map create a new entry
           if (pos == ptr2nr.end())
             {
+              NETGEN_DEBUG_LOG(logger, "Didn't find pointer, create new registry entry at " +
+                               std::to_string(ptr_count));
               ptr2nr[reg_ptr] = ptr_count++;
               if(typeid(*p) == typeid(T))
                 if (std::is_constructible<T>::value)
                                {
+                                 NETGEN_DEBUG_LOG(logger, "Store standard class pointer (no virt. inh,...)");
                                  return (*this) << -1 & (*p);
                                }
                 else
@@ -395,6 +441,7 @@ namespace ngcore
                     throw std::runtime_error(std::string("Archive error: Polymorphic type ")
                                              + Demangle(typeid(*p).name())
                                              + " not registered for archive");
+                  NETGEN_DEBUG_LOG(logger, "Store a possibly more complicated pointer");
                   return (*this) << -3 << Demangle(typeid(*p).name()) & (*p);
                 }
             }
@@ -402,27 +449,39 @@ namespace ngcore
             {
               (*this) & pos->second;
               bool downcasted = !(reg_ptr == static_cast<void*>(p) );
+              NETGEN_DEBUG_LOG(logger, "Store a the existing position in registry at " +
+                               std::to_string(pos->second));
+              NETGEN_DEBUG_LOG(logger, std::string("Pointer ") + (downcasted ? "needs " : "doesn't need ") +
+                               "downcasting");
               // store if the class has been downcasted and the name
               (*this) << downcasted << Demangle(typeid(*p).name());
             }
         }
       else
         {
+          NETGEN_DEBUG_LOG(logger, "Reading pointer of type " + Demangle(typeid(T).name()));
           int nr;
           (*this) & nr;
           if (nr == -2) // restore a nullptr
+            {
+              NETGEN_DEBUG_LOG(logger, "Loading a nullptr");
               p = nullptr;
+            }
           else if (nr == -1) // create a new pointer of standard type (no virtual or multiple inheritance,...)
             {
+              NETGEN_DEBUG_LOG(logger, "Load a new pointer to a simple class");
               p = detail::constructIfPossible<T>();
               nr2ptr.push_back(p);
               (*this) & *p;
             }
           else if(nr == -3) // restore one of our registered classes that can have multiple inheritance,...
             {
+              NETGEN_DEBUG_LOG(logger, "Load a new pointer to a potentially more complicated class "
+                               "(allows for multiple/virtual inheritance,...)");
               // As stated above, we want this special behaviour only for our classes that implement DoArchive
               std::string name;
               (*this) & name;
+              NETGEN_DEBUG_LOG(logger, "Name = " + name);
               auto info = GetArchiveRegister(name);
               // the creator creates a new object of type name, and returns a void* pointing
               // to T (which may have an offset)
@@ -434,9 +493,13 @@ namespace ngcore
             }
           else
             {
+              NETGEN_DEBUG_LOG(logger, "Restoring pointer to already existing object at registry position " +
+                               std::to_string(nr));
               bool downcasted;
               std::string name;
               (*this) & downcasted & name;
+              NETGEN_DEBUG_LOG(logger, std::string(downcasted ? "Downcasted" : "Not downcasted") +
+                               " object of type " + name);
               if(downcasted)
                 {
                   // if the class has been downcasted we can assume it is in the register
@@ -536,7 +599,7 @@ namespace ngcore
     {
       static_assert(detail::all_of_tmpl<std::is_base_of<Bases,T>::value...>,
                     "Variadic template arguments must be base classes of T");
-      detail::ClassArchiveInfo info;
+      detail::ClassArchiveInfo info {};
       info.creator = [this,&info](const std::type_info& ti) -> void*
                      { return typeid(T) == ti ? detail::constructIfPossible<T>()
                          : Archive::Caster<T, Bases...>::tryUpcast(ti, detail::constructIfPossible<T>()); };
@@ -643,6 +706,9 @@ namespace ngcore
     BinaryInArchive (const std::string& filename)
       : BinaryInArchive(std::make_shared<std::ifstream>(filename)) { ; }
 
+    const VersionInfo& GetVersion(const std::string& library) override
+    { return version_map[library]; }
+
     using Archive::operator&;
     Archive & operator & (double & d) override
     { Read(d); return *this; }
@@ -758,6 +824,9 @@ namespace ngcore
     TextInArchive (const std::string& filename)
       : TextInArchive(std::make_shared<std::ifstream>(filename)) {}
 
+    const VersionInfo& GetVersion(const std::string& library) override
+    { return version_map[library]; }
+
     using Archive::operator&;
     Archive & operator & (double & d) override
     { *stream >> d; return *this; }
@@ -805,7 +874,7 @@ namespace ngcore
     }
   };
 
-#ifdef NG_PYTHON
+#ifdef NETGEN_PYTHON
 
   template<typename ARCHIVE>
   class PyArchive : public ARCHIVE
@@ -813,7 +882,11 @@ namespace ngcore
   private:
     pybind11::list lst;
     size_t index = 0;
+  protected:
     using ARCHIVE::stream;
+    using ARCHIVE::version_map;
+    using ARCHIVE::logger;
+    using ARCHIVE::GetLibraryVersions;
   public:
     PyArchive(const pybind11::object& alst = pybind11::none()) :
       ARCHIVE(std::make_shared<std::stringstream>()),
@@ -821,8 +894,13 @@ namespace ngcore
     {
       ARCHIVE::shallow_to_python = true;
       if(Input())
-        stream = std::make_shared<std::stringstream>
-          (pybind11::cast<pybind11::bytes>(lst[pybind11::len(lst)-1]));
+        {
+          stream = std::make_shared<std::stringstream>
+            (pybind11::cast<pybind11::bytes>(lst[pybind11::len(lst)-1]));
+          *this & version_map;
+          stream = std::make_shared<std::stringstream>
+            (pybind11::cast<pybind11::bytes>(lst[pybind11::len(lst)-2]));
+        }
     }
 
     using ARCHIVE::Output;
@@ -831,39 +909,45 @@ namespace ngcore
     using ARCHIVE::operator&;
     using ARCHIVE::operator<<;
     using ARCHIVE::GetVersion;
-    void ShallowOutPython(pybind11::object val) override { lst.append(val); }
+    void ShallowOutPython(const pybind11::object& val) override { lst.append(val); }
     pybind11::object ShallowInPython() override { return lst[index++]; }
 
     pybind11::list WriteOut()
     {
       FlushBuffer();
       lst.append(pybind11::bytes(std::static_pointer_cast<std::stringstream>(stream)->str()));
+      stream = std::make_shared<std::stringstream>();
+      *this & GetLibraryVersions();
       return lst;
     }
   };
 
   template<typename T, typename T_ARCHIVE_OUT=BinaryOutArchive, typename T_ARCHIVE_IN=BinaryInArchive>
-  auto NGSPickle(bool printoutput=false)
+  auto NGSPickle()
   {
-    return pybind11::pickle([printoutput](T* self)
+    return pybind11::pickle([](T* self)
                       {
                         PyArchive<T_ARCHIVE_OUT> ar;
                         ar & self;
                         auto output = pybind11::make_tuple(ar.WriteOut());
-                        if(printoutput)
-                          pybind11::print("pickle output of", Demangle(typeid(T).name()),"=", output);
+                        NETGEN_DEBUG_LOG(GetLogger("Archive"), "pickling output for object of type " +
+                                         Demangle(typeid(T).name()) + " = " +
+                                         std::string(pybind11::str(output)));
                         return output;
                       },
                       [](pybind11::tuple state)
                       {
                         T* val = nullptr;
+                        NETGEN_DEBUG_LOG(GetLogger("Archive"), "State for unpickling of object of type " +
+                                         Demangle(typeid(T).name()) + " = " +
+                                         std::string(pybind11::str(state[0])));
                         PyArchive<T_ARCHIVE_IN> ar(state[0]);
                         ar & val;
                         return val;
                       });
   }
 
-#endif // NG_PYTHON
+#endif // NETGEN_PYTHON
 } // namespace ngcore
 
 #endif // NETGEN_CORE_ARCHIVE_HPP
diff --git a/libsrc/core/logging.cpp b/libsrc/core/logging.cpp
new file mode 100644
index 00000000..467255cd
--- /dev/null
+++ b/libsrc/core/logging.cpp
@@ -0,0 +1,109 @@
+
+#include "logging.hpp"
+
+#ifdef NETGEN_USE_SPDLOG
+
+#include <spdlog/sinks/ansicolor_sink.h>
+#include <spdlog/sinks/basic_file_sink.h>
+
+#endif // NETGEN_USE_SPDLOG
+
+namespace ngcore
+{
+#ifdef NETGEN_USE_SPDLOG
+  namespace detail
+  {
+    std::vector<std::shared_ptr<spdlog::sinks::sink>>& GetDefaultSinks()
+    {
+      static std::vector<std::shared_ptr<spdlog::sinks::sink>> sinks =
+        { std::make_shared<spdlog::sinks::ansicolor_stdout_sink_mt>() };
+      return sinks;
+    }
+    std::shared_ptr<spdlog::logger> CreateDefaultLogger(const std::string& name)
+    {
+      auto& default_sinks = GetDefaultSinks();
+      auto logger = std::make_shared<spdlog::logger>(name, default_sinks.begin(), default_sinks.end());
+      spdlog::details::registry::instance().register_and_init(logger);
+      return logger;
+    }
+  } // namespace detail
+
+  std::shared_ptr<spdlog::logger> GetLogger(const std::string& name)
+  {
+    auto logger = spdlog::get(name);
+    if(!logger)
+      logger = detail::CreateDefaultLogger(name);
+    return logger;
+  }
+
+  void SetLoggingLevel(spdlog::level::level_enum level, const std::string& name)
+  {
+    if(!name.empty())
+      spdlog::get(name)->set_level(level);
+    else
+      spdlog::set_level(level);
+  }
+
+  void AddFileSink(const std::string& filename, spdlog::level::level_enum level, const std::string& logger)
+  {
+    auto sink = std::make_shared<spdlog::sinks::basic_file_sink_mt>(filename);
+    sink->set_level(level);
+    if(!logger.empty())
+      GetLogger(logger)->sinks().push_back(sink);
+    else
+      {
+        detail::GetDefaultSinks().push_back(sink);
+        spdlog::details::registry::instance().apply_all([sink](auto logger) { logger->sinks().push_back(sink); });
+      }
+  }
+
+  void AddConsoleSink(spdlog::level::level_enum level, const std::string& logger)
+  {
+    auto sink = std::make_shared<spdlog::sinks::ansicolor_stdout_sink_mt>();
+    sink->set_level(level);
+    if(!logger.empty())
+      GetLogger(logger)->sinks().push_back(sink);
+    else
+      {
+        detail::GetDefaultSinks().push_back(sink);
+        spdlog::details::registry::instance().apply_all([sink](auto logger) { logger->sinks().push_back(sink); });
+      }
+  }
+
+  void ClearLoggingSinks(const std::string& logger)
+  {
+    if(!logger.empty())
+      GetLogger(logger)->sinks().clear();
+    else
+      {
+        detail::GetDefaultSinks().clear();
+        spdlog::details::registry::instance().apply_all([](auto logger) { logger->sinks().clear(); });
+      }
+  }
+
+  void FlushOnLoggingLevel(spdlog::level::level_enum level, const std::string& logger)
+  {
+    if(!logger.empty())
+      GetLogger(logger)->flush_on(level);
+    else
+      spdlog::flush_on(level);
+  }
+
+#else // NETGEN_USE_SPDLOG
+
+  // Dummy functions if no spdlog is available
+
+  std::shared_ptr<spdlog::logger> GetLogger(const std::string& /*unused*/)
+  {
+    return std::make_shared<spdlog::logger>();
+  }
+  void SetLoggingLevel(spdlog::level::level_enum /*unused*/, const std::string& /*unused*/) {}
+  void AddFileSink(const std::string& /*unused*/, spdlog::level::level_enum /*unused*/,
+                   const std::string& /*unused*/)
+  {}
+  void AddConsoleSink(spdlog::level::level_enum /*unused*/, const std::string& /*unused*/) {}
+  void ClearLoggingSinks(const std::string& /*unused*/) {}
+  void FlushOnLoggingLevel(spdlog::level::level_enum /*unused*/, const std::string& /*unused*/) {}
+
+#endif // NETGEN_USE_SPDLOG
+} //namespace ngcore
diff --git a/libsrc/core/logging.hpp b/libsrc/core/logging.hpp
new file mode 100644
index 00000000..8952a5f6
--- /dev/null
+++ b/libsrc/core/logging.hpp
@@ -0,0 +1,87 @@
+#ifndef NETGEN_CORE_LOGGING_HPP
+#define NETGEN_CORE_LOGGING_HPP
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "ngcore_api.hpp"
+
+#ifdef NETGEN_USE_SPDLOG
+
+#ifdef NETGEN_LOG_DEBUG
+#define SPDLOG_DEBUG_ON
+#endif // NETGEN_LOG_DEBUG
+
+#include <spdlog/logger.h>
+#include <spdlog/sinks/sink.h>
+#include <spdlog/spdlog.h>
+
+#define NETGEN_DEBUG_LOG(logger, ...) SPDLOG_DEBUG(logger, __VA_ARGS__)
+
+#else // NETGEN_USE_SPDLOG
+
+#include <iostream>
+
+namespace spdlog
+{
+  // Dummys if Netgen is compiled with USE_SPDLOG=OFF.
+  class logger
+  {
+  public:
+    template<typename T>
+    void trace(const T& /*unused*/) {}
+    template<typename T>
+    void debug(const T& /*unused*/) {}
+    template<typename T>
+    void info(const T& text) { std::cout << text << std::endl; }
+    template<typename T>
+    void warn(const T& text) { std::cout << text << std::endl; }
+    template<typename T>
+    void error(const T& text) { std::cout << text << std::endl; }
+    template<typename T>
+    void critical(const T& text) { std::cout << text << std::endl; }
+  };
+
+  namespace level
+  {
+    enum level_enum
+      {
+       trace = 0,
+       debug = 1,
+       info = 2,
+       warn = 3,
+       err = 4,
+       critical = 5,
+       off = 6
+      };
+  } // namespace level
+
+  namespace sinks
+  {
+    class sink {};
+  } // namespace sinks
+
+} //namespace spdlog
+
+#define NETGEN_DEBUG_LOG(logger, ...)
+
+#endif // NETGEN_USE_SPDLOG
+
+namespace ngcore
+{
+  namespace detail
+  {
+    std::vector<std::shared_ptr<spdlog::sinks::sink>>& GetDefaultSinks();
+    inline std::shared_ptr<spdlog::logger> CreateDefaultLogger(const std::string& name);
+  } //namespace detail
+
+  NGCORE_API std::shared_ptr<spdlog::logger> GetLogger(const std::string& name);
+  NGCORE_API void SetLoggingLevel(spdlog::level::level_enum level, const std::string& name);
+  NGCORE_API void AddFileSink(const std::string& filename, spdlog::level::level_enum level, const std::string& logger);
+  NGCORE_API void AddConsoleSink(spdlog::level::level_enum level, const std::string& logger);
+  NGCORE_API void ClearLoggingSinks(const std::string& logger);
+  NGCORE_API void FlushOnLoggingLevel(spdlog::level::level_enum level, const std::string& logger);
+} // namespace ngcore
+
+#endif // NETGEN_CORE_LOGGING_HPP
diff --git a/libsrc/core/ngcore.hpp b/libsrc/core/ngcore.hpp
index 1c8fa591..ea7f8eab 100644
--- a/libsrc/core/ngcore.hpp
+++ b/libsrc/core/ngcore.hpp
@@ -2,6 +2,7 @@
 #define NETGEN_CORE_NGCORE_HPP
 
 #include "archive.hpp"
+#include "logging.hpp"
 #include "version.hpp"
 
 #endif // NETGEN_CORE_NGCORE_HPP
diff --git a/libsrc/core/ngcore_api.hpp b/libsrc/core/ngcore_api.hpp
index c08d0ac9..5c65cf3a 100644
--- a/libsrc/core/ngcore_api.hpp
+++ b/libsrc/core/ngcore_api.hpp
@@ -5,8 +5,8 @@
         #define NGCORE_API_EXPORT __declspec(dllexport)
         #define NGCORE_API_IMPORT __declspec(dllimport)
 #else
-        #define NGCORE_API_EXPORT
-        #define NGCORE_API_IMPORT
+        #define NGCORE_API_EXPORT __attribute__((visibility("default")))
+        #define NGCORE_API_IMPORT __attribute__((visibility("default")))
 #endif
 
 #ifdef NGCORE_EXPORTS
diff --git a/libsrc/core/python_ngcore.cpp b/libsrc/core/python_ngcore.cpp
new file mode 100644
index 00000000..b7624e43
--- /dev/null
+++ b/libsrc/core/python_ngcore.cpp
@@ -0,0 +1,30 @@
+
+#include <pybind11/pybind11.h>
+
+#include "logging.hpp"
+
+namespace py = pybind11;
+using namespace ngcore;
+
+PYBIND11_MODULE(pyngcore, m) // NOLINT
+{
+  py::enum_<spdlog::level::level_enum>(m, "LOG_LEVEL", "Logging level")
+    .value("Trace", spdlog::level::trace)
+    .value("Debug", spdlog::level::debug)
+    .value("Info", spdlog::level::info)
+    .value("Warn", spdlog::level::warn)
+    .value("Error", spdlog::level::err)
+    .value("Critical", spdlog::level::critical)
+    .value("Off", spdlog::level::off);
+
+  m.def("SetLoggingLevel", &SetLoggingLevel, py::arg("level"), py::arg("logger")="",
+        "Set logging level, if name is given only to the specific logger, else set the global logging level");
+  m.def("AddFileSink", &AddFileSink, py::arg("filename"), py::arg("level"), py::arg("logger")="",
+        "Add File sink, either only to logger specified or globally to all loggers");
+  m.def("AddConsoleSink", &AddConsoleSink, py::arg("level"), py::arg("logger")="",
+        "Add console output for specific logger or all if none given");
+  m.def("ClearLoggingSinks", &ClearLoggingSinks, py::arg("logger")="",
+        "Clear sinks of specific logger, or all if none given");
+  m.def("FlushOnLoggingLevel", &FlushOnLoggingLevel, py::arg("level"), py::arg("logger")="",
+        "Flush every message with level at least `level` for specific logger or all loggers if none given.");
+}
diff --git a/libsrc/general/CMakeLists.txt b/libsrc/general/CMakeLists.txt
index 00c59ea2..39b63d4c 100644
--- a/libsrc/general/CMakeLists.txt
+++ b/libsrc/general/CMakeLists.txt
@@ -6,6 +6,10 @@ add_library(gen OBJECT
         mpi_interface.cpp gzstream.cpp
         )
 
+if(NOT WIN32)
+  target_link_libraries(gen ngcore)
+endif(NOT WIN32)
+
 set_target_properties( gen PROPERTIES POSITION_INDEPENDENT_CODE ON )
 
 install( FILES ngexception.hpp DESTINATION ${NG_INSTALL_DIR_INCLUDE} COMPONENT netgen_devel )
diff --git a/libsrc/gprim/CMakeLists.txt b/libsrc/gprim/CMakeLists.txt
index 3957476a..ac4b8f11 100644
--- a/libsrc/gprim/CMakeLists.txt
+++ b/libsrc/gprim/CMakeLists.txt
@@ -3,6 +3,9 @@ add_library(gprim OBJECT
         adtree.cpp geom2d.cpp geom3d.cpp geomfuncs.cpp 
         geomtest3d.cpp transform3d.cpp spline.cpp splinegeometry.cpp
         )
+if(NOT WIN32)
+  target_link_libraries(gprim ngcore)
+endif(NOT WIN32)
 
 set_target_properties( gprim PROPERTIES POSITION_INDEPENDENT_CODE ON )
 
diff --git a/libsrc/linalg/CMakeLists.txt b/libsrc/linalg/CMakeLists.txt
index a5a5a4f2..9f35d751 100644
--- a/libsrc/linalg/CMakeLists.txt
+++ b/libsrc/linalg/CMakeLists.txt
@@ -4,6 +4,10 @@ add_library( la OBJECT
 
 set_target_properties(la PROPERTIES POSITION_INDEPENDENT_CODE ON )
 
+if(NOT WIN32)
+  target_link_libraries(la ngcore)
+endif(NOT WIN32)
+
 install(FILES
   densemat.hpp linalg.hpp opti.hpp
   polynomial.hpp vector.hpp
diff --git a/libsrc/meshing/python_mesh.cpp b/libsrc/meshing/python_mesh.cpp
index 6360174a..d349dfcf 100644
--- a/libsrc/meshing/python_mesh.cpp
+++ b/libsrc/meshing/python_mesh.cpp
@@ -506,7 +506,6 @@ DLL_HEADER void ExportNetgenMeshing(py::module &m)
           )
     */
     
-    .def("__str__", &ToString<Mesh>)
     .def_property_readonly("_timestamp", &Mesh::GetTimeStamp)
     .def("Load",  FunctionPointer 
 	 ([](Mesh & self, const string & filename)
diff --git a/libsrc/occ/CMakeLists.txt b/libsrc/occ/CMakeLists.txt
index 831a3875..a244e85b 100644
--- a/libsrc/occ/CMakeLists.txt
+++ b/libsrc/occ/CMakeLists.txt
@@ -9,7 +9,7 @@ if(USE_GUI)
 endif(USE_GUI)
 
 if(NOT WIN32)
-    target_link_libraries( occ ${OCC_LIBRARIES} ${PYTHON_LIBRARIES})
+    target_link_libraries( occ ngcore ${OCC_LIBRARIES} ${PYTHON_LIBRARIES})
     install( TARGETS occ ${NG_INSTALL_DIR})
     if (USE_GUI)
         target_link_libraries( occvis occ )
diff --git a/libsrc/stlgeom/CMakeLists.txt b/libsrc/stlgeom/CMakeLists.txt
index 3620c496..7b87a649 100644
--- a/libsrc/stlgeom/CMakeLists.txt
+++ b/libsrc/stlgeom/CMakeLists.txt
@@ -4,8 +4,7 @@ add_library(stl ${NG_LIB_TYPE}
         )
 
 if(NOT WIN32)
-    target_link_libraries( stl mesh  ${PYTHON_LIBRARIES})
-    target_link_libraries( stl ${PYTHON_LIBRARIES})
+    target_link_libraries( stl ngcore mesh ${PYTHON_LIBRARIES})
     install( TARGETS stl ${NG_INSTALL_DIR})
 endif(NOT WIN32)
 
diff --git a/libsrc/visualization/CMakeLists.txt b/libsrc/visualization/CMakeLists.txt
index 8f803d92..f1c82976 100644
--- a/libsrc/visualization/CMakeLists.txt
+++ b/libsrc/visualization/CMakeLists.txt
@@ -10,7 +10,7 @@ endif(USE_GUI)
 add_library(visual ${NG_LIB_TYPE} ${LIB_VISUAL_SOURCES})
 
 if(NOT WIN32)
-    target_link_libraries( visual ${PYTHON_LIBRARIES} ${MPI_CXX_LIBRARIES} ${OPENGL_LIBRARIES} )
+    target_link_libraries( visual ngcore ${PYTHON_LIBRARIES} ${MPI_CXX_LIBRARIES} ${OPENGL_LIBRARIES} )
     install( TARGETS visual ${NG_INSTALL_DIR})
 endif(NOT WIN32)
 
diff --git a/tests/build_nospdlog.sh b/tests/build_nospdlog.sh
new file mode 100644
index 00000000..2fedbef2
--- /dev/null
+++ b/tests/build_nospdlog.sh
@@ -0,0 +1,8 @@
+cd
+mkdir -p build/netgen
+cd build/netgen
+cmake ../../src/netgen -DUSE_CCACHE=ON -DUSE_SPDLOG=OFF -DCMAKE_CXX_COMPILER=clang++ \
+      -DCMAKE_C_COMPILER=clang
+make -j12
+make install
+
diff --git a/tests/catch/CMakeLists.txt b/tests/catch/CMakeLists.txt
index fc0ebe41..58386884 100644
--- a/tests/catch/CMakeLists.txt
+++ b/tests/catch/CMakeLists.txt
@@ -3,8 +3,7 @@ if(ENABLE_UNIT_TESTS)
 add_custom_target(unit_tests)
 
 # Build catch_main test object
-message("netgen include dir = ${NETGEN_INCLUDE_DIR_ABSOLUTE} --------------------------------------")
-include_directories(${CATCH_INCLUDE_DIR} ${CMAKE_CURRENT_SOURCE_DIR}/../../libsrc/include})
+include_directories(${CATCH_INCLUDE_DIR} ${CMAKE_CURRENT_SOURCE_DIR}/../../libsrc/include ${SPDLOG_INCLUDE_DIR})
 add_library(catch_main STATIC main.cpp)
 set_target_properties(catch_main PROPERTIES CXX_STANDARD 17)
 add_dependencies(unit_tests catch_main)
@@ -15,11 +14,7 @@ add_test(NAME unit_tests_built COMMAND ${CMAKE_COMMAND} --build . --target unit_
 
 macro(add_unit_test name sources)
   add_executable(test_${name} ${sources} )
-  if (WIN32)
-    target_link_libraries(test_${name} ngcore catch_main)
-  else(WIN32)
-    target_link_libraries(test_${name} ngcore catch_main)
-  endif(WIN32)
+  target_link_libraries(test_${name} ngcore catch_main)
 
   add_dependencies(unit_tests test_${name})
   add_test(NAME unit_${name} COMMAND test_${name})