diff --git a/src/App/Expression.cpp b/src/App/Expression.cpp
index f2314627f5..2750c9802a 100644
--- a/src/App/Expression.cpp
+++ b/src/App/Expression.cpp
@@ -434,7 +434,7 @@ static Py::Object _pyObjectFromAny(const App::any &value, const Expression *e) {
     } else if (is_type(value,typeid(bool)))
         return Py::Boolean(cast<bool>(value));
     else if (is_type(value,typeid(std::string)))
-        return Py::String(cast<string>(value));
+        return Py::String(cast<std::string>(value));
     else if (is_type(value,typeid(const char*)))
         return Py::String(cast<const char*>(value));
 
diff --git a/src/App/MergeDocuments.cpp b/src/App/MergeDocuments.cpp
index fafcab3cc6..10386f75ff 100644
--- a/src/App/MergeDocuments.cpp
+++ b/src/App/MergeDocuments.cpp
@@ -26,6 +26,8 @@
 #endif
 
 #include <QCoreApplication>
+#include <zipios++/zipinputstream.h>
+
 #include <App/Document.h>
 #include <Base/Reader.h>
 #include <Base/Writer.h>
diff --git a/src/Base/Axis.cpp b/src/Base/Axis.cpp
index 8c0450906c..3b0dad5edd 100644
--- a/src/Base/Axis.cpp
+++ b/src/Base/Axis.cpp
@@ -23,6 +23,7 @@
 #include "PreCompiled.h"
 
 #include "Axis.h"
+#include "Placement.h"
 
 using namespace Base;
 
diff --git a/src/Base/Axis.h b/src/Base/Axis.h
index b7bac366e0..6b36855082 100644
--- a/src/Base/Axis.h
+++ b/src/Base/Axis.h
@@ -24,11 +24,13 @@
 #ifndef BASE_AXIS_H
 #define BASE_AXIS_H
 
-#include "Placement.h"
+#include <FCGlobal.h>
+
 #include "Vector3D.h"
 
 namespace Base
 {
+class Placement;
 
 /**
  * The Axis class.
diff --git a/src/Base/Base64.cpp b/src/Base/Base64.cpp
index dd426c8c5b..ba4c4dfb04 100644
--- a/src/Base/Base64.cpp
+++ b/src/Base/Base64.cpp
@@ -31,7 +31,7 @@ These modifications are Copyright (c) 2019 Zheng Lei (realthunder.dev@gmail.com)
 #include "PreCompiled.h"
 
 #ifndef _PreComp_
-#include <string>
+#include <array>
 #endif
 
 #include "Base64.h"
diff --git a/src/Base/Base64.h b/src/Base/Base64.h
index f60a4b5a8c..ac26072bcb 100644
--- a/src/Base/Base64.h
+++ b/src/Base/Base64.h
@@ -32,9 +32,7 @@ These modifications are Copyright (c) 2019 Zheng Lei (realthunder.dev@gmail.com)
 #define BASE_BASE64_H
 
 #include <array>
-#include <memory>
 #include <string>
-#include <vector>
 
 #include "FCGlobal.h"
 
diff --git a/src/Base/Builder3D.cpp b/src/Base/Builder3D.cpp
index bd461b60ee..806ef38f89 100644
--- a/src/Base/Builder3D.cpp
+++ b/src/Base/Builder3D.cpp
@@ -25,11 +25,8 @@
 
 #ifndef _PreComp_
 #include <algorithm>
-#include <cassert>
-#include <exception>
 #include <string>
 #include <string_view>
-#include <fstream>
 #include <boost/algorithm/string.hpp>
 #include <boost/algorithm/string/predicate.hpp>
 #include <boost/lexical_cast.hpp>
@@ -40,9 +37,7 @@
 #include "Console.h"
 #include "Exception.h"
 #include "FileInfo.h"
-#include "Matrix.h"
 #include "Stream.h"
-#include "Tools.h"
 
 
 using namespace Base;
diff --git a/src/Base/Builder3D.h b/src/Base/Builder3D.h
index df43ba08e9..d3375f5ad3 100644
--- a/src/Base/Builder3D.h
+++ b/src/Base/Builder3D.h
@@ -34,6 +34,8 @@
 #include <FCGlobal.h>
 #endif
 
+#include "Placement.h"
+
 namespace Base
 {
 class Matrix4D;
diff --git a/src/Base/Console.cpp b/src/Base/Console.cpp
index 450864855a..9e9b43bd1d 100644
--- a/src/Base/Console.cpp
+++ b/src/Base/Console.cpp
@@ -34,7 +34,6 @@
 #endif
 
 #include "Console.h"
-#include "Exception.h"
 #include "PyObjectBase.h"
 #include <QCoreApplication>
 
diff --git a/src/Base/CoordinateSystem.cpp b/src/Base/CoordinateSystem.cpp
index 4134bed8f9..87da260b6e 100644
--- a/src/Base/CoordinateSystem.cpp
+++ b/src/Base/CoordinateSystem.cpp
@@ -26,6 +26,8 @@
 #include "CoordinateSystem.h"
 #include "Exception.h"
 #include "Matrix.h"
+#include "Placement.h"
+#include "Rotation.h"
 
 
 using namespace Base;
diff --git a/src/Base/CoordinateSystem.h b/src/Base/CoordinateSystem.h
index f38bb016be..20264d130b 100644
--- a/src/Base/CoordinateSystem.h
+++ b/src/Base/CoordinateSystem.h
@@ -28,6 +28,8 @@
 
 namespace Base
 {
+class Rotation;
+
 /**
  * Describes a right-handed coordinate system in 3D space.
  \author Werner Mayer
diff --git a/src/Base/Factory.cpp b/src/Base/Factory.cpp
index 8b937d3228..c3967f43f2 100644
--- a/src/Base/Factory.cpp
+++ b/src/Base/Factory.cpp
@@ -31,7 +31,6 @@
 #include "Factory.h"
 #include "Console.h"
 
-
 using namespace Base;
 
 
diff --git a/src/Base/FileInfo.cpp b/src/Base/FileInfo.cpp
index d10a3c65b1..082a20f6b8 100644
--- a/src/Base/FileInfo.cpp
+++ b/src/Base/FileInfo.cpp
@@ -26,10 +26,9 @@
 
 #ifndef _PreComp_
 #include <algorithm>
-#include <cassert>
 #include <codecvt>
 #include <cstring>
-#include <locale>
+#include <iostream>
 #if defined(FC_OS_LINUX) || defined(FC_OS_CYGWIN) || defined(FC_OS_MACOSX) || defined(FC_OS_BSD)
 #include <dirent.h>
 #include <unistd.h>
@@ -45,6 +44,7 @@
 #include "FileInfo.h"
 #include "Exception.h"
 #include "Stream.h"
+#include "TimeInfo.h"
 
 
 using namespace Base;
diff --git a/src/Base/FileInfo.h b/src/Base/FileInfo.h
index 7e0ddbb9a4..cfe21dc03c 100644
--- a/src/Base/FileInfo.h
+++ b/src/Base/FileInfo.h
@@ -28,16 +28,18 @@
 #include <filesystem>
 #include <string>
 #include <vector>
-#include <Base/TimeInfo.h>
+
+#include <FCGlobal.h>
 
 
 namespace Base
 {
+class TimeInfo;
 
 /// When reading and writing a character stream, the incoming data can be dumped into the stream
 /// unaltered (if it contains only data that is valid in the current XML character set), or it can
 /// be Base64-encoded. This enum is used by Reader and Writer to distinguish the two cases.
-enum class CharStreamFormat
+enum class CharStreamFormat : size_t
 {
     Raw,
     Base64Encoded
diff --git a/src/Base/GeometryPyCXX.h b/src/Base/GeometryPyCXX.h
index 709c8a689e..0bbb300aac 100644
--- a/src/Base/GeometryPyCXX.h
+++ b/src/Base/GeometryPyCXX.h
@@ -28,17 +28,21 @@
 #include <FCGlobal.h>
 
 #include <Base/BoundBoxPy.h>
-#include <Base/Matrix.h>
 #include <Base/MatrixPy.h>
-#include <Base/Rotation.h>
 #include <Base/RotationPy.h>
-#include <Base/Placement.h>
 #include <Base/PlacementPy.h>
-#include <Base/Vector3D.h>
 
 
 namespace Base
 {
+class Matrix4D;
+class Rotation;
+class Placement;
+template<typename T>
+class Vector3;
+using Vector3d = Vector3<double>;
+using Vector3f = Vector3<float>;
+
 template<typename T>
 inline Vector3<T> getVectorFromTuple(PyObject* py)
 {
diff --git a/src/Base/InputSource.cpp b/src/Base/InputSource.cpp
index 9ed9f294bd..903dcc2121 100644
--- a/src/Base/InputSource.cpp
+++ b/src/Base/InputSource.cpp
@@ -23,6 +23,8 @@
 
 #include "PreCompiled.h"
 
+#include <istream>
+
 #include <qglobal.h>
 #if QT_VERSION < 0x060000
 #include <QTextCodec>
diff --git a/src/Base/InputSource.h b/src/Base/InputSource.h
index d042a19a0c..d89d9398b4 100644
--- a/src/Base/InputSource.h
+++ b/src/Base/InputSource.h
@@ -34,7 +34,6 @@
 
 #ifndef XERCES_CPP_NAMESPACE_BEGIN
 #define XERCES_CPP_NAMESPACE_QUALIFIER
-using namespace XERCES_CPP_NAMESPACE;
 namespace XERCES_CPP_NAMESPACE
 {
 class BinInputStream;
diff --git a/src/Base/Interpreter.h b/src/Base/Interpreter.h
index 1044807059..f2787a4d22 100644
--- a/src/Base/Interpreter.h
+++ b/src/Base/Interpreter.h
@@ -86,9 +86,6 @@
 namespace Base
 {
 
-using std::string;
-using std::vector;
-
 
 class BaseExport PyException: public Exception
 {
diff --git a/src/Base/Matrix.h b/src/Base/Matrix.h
index d8487fe7d2..b177abb0fe 100644
--- a/src/Base/Matrix.h
+++ b/src/Base/Matrix.h
@@ -24,8 +24,9 @@
 #ifndef BASE_MATRIX_H
 #define BASE_MATRIX_H
 
-#include <string>
 #include <array>
+#include <cmath>
+#include <string>
 
 #include "Vector3D.h"
 #ifndef FC_GLOBAL_H
diff --git a/src/Base/Observer.h b/src/Base/Observer.h
index 85753467a2..ba94365bd0 100644
--- a/src/Base/Observer.h
+++ b/src/Base/Observer.h
@@ -25,7 +25,6 @@
 #ifndef BASE_OBSERVER_H
 #define BASE_OBSERVER_H
 
-#include <cassert>
 #include <cstring>
 #include <set>
 #include "Console.h"
diff --git a/src/Base/Parameter.cpp b/src/Base/Parameter.cpp
index 3e02aae6e6..ecc8cda610 100644
--- a/src/Base/Parameter.cpp
+++ b/src/Base/Parameter.cpp
@@ -26,7 +26,7 @@
 
 #ifndef _PreComp_
 #include <algorithm>
-#include <cassert>
+#include <iostream>
 #include <memory>
 #include <xercesc/dom/DOM.hpp>
 #include <xercesc/framework/LocalFileFormatTarget.hpp>
diff --git a/src/Base/Parameter.h b/src/Base/Parameter.h
index 80edcba298..2174d25c43 100644
--- a/src/Base/Parameter.h
+++ b/src/Base/Parameter.h
@@ -45,10 +45,6 @@ using PyObject = struct _object;
 #undef isalnum
 #endif
 
-#ifdef FC_OS_LINUX
-#include <sstream>
-#endif
-
 #include <map>
 #include <vector>
 #include <boost/signals2.hpp>
@@ -67,7 +63,6 @@ using PyObject = struct _object;
 
 #ifndef XERCES_CPP_NAMESPACE_BEGIN
 #define XERCES_CPP_NAMESPACE_QUALIFIER
-using namespace XERCES_CPP_NAMESPACE;
 namespace XERCES_CPP_NAMESPACE
 {
 class DOMNode;
diff --git a/src/Base/Persistence.cpp b/src/Base/Persistence.cpp
index 7dc3f7d42e..3c4aa62f7a 100644
--- a/src/Base/Persistence.cpp
+++ b/src/Base/Persistence.cpp
@@ -27,6 +27,8 @@
 #include <cassert>
 #endif
 
+#include <zipios++/zipinputstream.h>
+
 #include "Exception.h"
 #include "Reader.h"
 #include "Writer.h"
diff --git a/src/Base/Placement.h b/src/Base/Placement.h
index 41bafc4faa..3189f5f056 100644
--- a/src/Base/Placement.h
+++ b/src/Base/Placement.h
@@ -26,7 +26,6 @@
 #include <string>
 
 #include "Rotation.h"
-#include "Vector3D.h"
 
 
 namespace Base
@@ -35,6 +34,10 @@ namespace Base
 class DualQuat;
 class Matrix4D;
 
+template<typename T>
+class Vector3;
+using Vector3d = Vector3<double>;
+
 /**
  * The Placement class.
  */
diff --git a/src/Base/ProgressIndicatorPy.cpp b/src/Base/ProgressIndicatorPy.cpp
index fffed5ff2e..78f756875e 100644
--- a/src/Base/ProgressIndicatorPy.cpp
+++ b/src/Base/ProgressIndicatorPy.cpp
@@ -23,6 +23,7 @@
 
 #include "PreCompiled.h"
 
+#include "Exception.h"
 #include "ProgressIndicatorPy.h"
 
 
diff --git a/src/Base/PyWrapParseTupleAndKeywords.h b/src/Base/PyWrapParseTupleAndKeywords.h
index db0d1acb8d..cc89265edf 100644
--- a/src/Base/PyWrapParseTupleAndKeywords.h
+++ b/src/Base/PyWrapParseTupleAndKeywords.h
@@ -26,7 +26,6 @@
 
 #include <Python.h>
 #include <array>
-#include <type_traits>
 
 namespace Base
 {
diff --git a/src/Base/Reader.cpp b/src/Base/Reader.cpp
index 63b85bfa81..69a8ecc23c 100644
--- a/src/Base/Reader.cpp
+++ b/src/Base/Reader.cpp
@@ -26,6 +26,7 @@
 #ifndef _PreComp_
 #include <memory>
 #include <xercesc/sax2/XMLReaderFactory.hpp>
+#include <xercesc/sax2/Attributes.hpp>
 #endif
 
 #include <locale>
@@ -34,6 +35,7 @@
 #include "Base64.h"
 #include "Base64Filter.h"
 #include "Console.h"
+#include "Exception.h"
 #include "InputSource.h"
 #include "Persistence.h"
 #include "Sequencer.h"
diff --git a/src/Base/Reader.h b/src/Base/Reader.h
index a11b1966a2..f26c0617c8 100644
--- a/src/Base/Reader.h
+++ b/src/Base/Reader.h
@@ -26,14 +26,12 @@
 #include <bitset>
 #include <map>
 #include <memory>
-#include <sstream>
 #include <string>
 
 #include <xercesc/framework/XMLPScanToken.hpp>
-#include <xercesc/sax2/Attributes.hpp>
 #include <xercesc/sax2/DefaultHandler.hpp>
 
-#include <boost/iostreams/concepts.hpp>
+#include <boost/iostreams/categories.hpp>
 
 #include "FileInfo.h"
 
@@ -44,14 +42,15 @@ class ZipInputStream;
 }
 #ifndef XERCES_CPP_NAMESPACE_BEGIN
 #define XERCES_CPP_NAMESPACE_QUALIFIER
-using namespace XERCES_CPP_NAMESPACE;
 namespace XERCES_CPP_NAMESPACE
 {
+class Attributes;
 class DefaultHandler;
 class SAX2XMLReader;
 }  // namespace XERCES_CPP_NAMESPACE
 #else
 XERCES_CPP_NAMESPACE_BEGIN
+class Attributes;
 class DefaultHandler;
 class SAX2XMLReader;
 XERCES_CPP_NAMESPACE_END
diff --git a/src/Base/Rotation.cpp b/src/Base/Rotation.cpp
index 623b41dd2d..da65a99808 100644
--- a/src/Base/Rotation.cpp
+++ b/src/Base/Rotation.cpp
@@ -22,7 +22,6 @@
 
 
 #include "PreCompiled.h"
-#include <array>
 
 #include <boost/algorithm/string/predicate.hpp>
 #include "Base/Exception.h"
diff --git a/src/Base/Sequencer.cpp b/src/Base/Sequencer.cpp
index e573943917..6a9197d50a 100644
--- a/src/Base/Sequencer.cpp
+++ b/src/Base/Sequencer.cpp
@@ -27,6 +27,7 @@
 #include <mutex>
 #include <vector>
 #include <algorithm>
+#include <cstdio>
 #endif
 
 #include "Sequencer.h"
diff --git a/src/Base/Sequencer.h b/src/Base/Sequencer.h
index bcc8761309..4d589cbf93 100644
--- a/src/Base/Sequencer.h
+++ b/src/Base/Sequencer.h
@@ -24,8 +24,6 @@
 #ifndef BASE_SEQUENCER_H
 #define BASE_SEQUENCER_H
 
-#include "Exception.h"
-
 
 namespace Base
 {
diff --git a/src/Base/Stream.cpp b/src/Base/Stream.cpp
index f95a4fa722..85ecbc99b4 100644
--- a/src/Base/Stream.cpp
+++ b/src/Base/Stream.cpp
@@ -25,9 +25,7 @@
 
 #ifndef _PreComp_
 #include <QBuffer>
-#include <QByteArray>
 #include <QIODevice>
-#include <cstring>
 #ifdef __GNUC__
 #include <cstdint>
 #endif
diff --git a/src/Base/Stream.h b/src/Base/Stream.h
index 94055cb118..5b2322bec5 100644
--- a/src/Base/Stream.h
+++ b/src/Base/Stream.h
@@ -29,7 +29,6 @@
 #endif
 
 #include <fstream>
-#include <iostream>
 #include <sstream>
 #include <string>
 #include <vector>
diff --git a/src/Base/Tools.cpp b/src/Base/Tools.cpp
index 71f6021bee..1c17850611 100644
--- a/src/Base/Tools.cpp
+++ b/src/Base/Tools.cpp
@@ -24,8 +24,6 @@
 #include "PreCompiled.h"
 #ifndef _PreComp_
 #include <sstream>
-#include <locale>
-#include <iostream>
 #include <QDateTime>
 #endif
 
diff --git a/src/Base/Tools.h b/src/Base/Tools.h
index 28675a5c72..43685506e5 100644
--- a/src/Base/Tools.h
+++ b/src/Base/Tools.h
@@ -27,16 +27,23 @@
 #ifndef FC_GLOBAL_H
 #include <FCGlobal.h>
 #endif
-#include <functional>
-#include <algorithm>
 #include <cmath>
-#include <iostream>
-#include <vector>
+#include <ostream>
 #include <string>
-#include <boost/signals2.hpp>
-#include <QString>
+#include <vector>
 
-// ----------------------------------------------------------------------------
+#include <boost/signals2/shared_connection_block.hpp>
+
+namespace boost
+{
+namespace signals2
+{
+class connection;
+}
+}  // namespace boost
+
+
+class QString;
 
 namespace Base
 {
diff --git a/src/Base/Tools2D.cpp b/src/Base/Tools2D.cpp
index e9e39f8b02..625f152ca5 100644
--- a/src/Base/Tools2D.cpp
+++ b/src/Base/Tools2D.cpp
@@ -25,7 +25,6 @@
 
 #ifndef _PreComp_
 #include <array>
-#include <cstdlib>
 #include <set>
 #endif
 
diff --git a/src/Base/Tools2D.h b/src/Base/Tools2D.h
index 61b4abbf22..251c8139bb 100644
--- a/src/Base/Tools2D.h
+++ b/src/Base/Tools2D.h
@@ -25,16 +25,22 @@
 
 #include <algorithm>
 #include <cmath>
-#include <cfloat>
-#include <cstdio>
 #include <list>
 #include <vector>
 
-#include "Vector3D.h"
 #ifndef FC_GLOBAL_H
 #include <FCGlobal.h>
 #endif
 
+// NOLINTBEGIN
+#ifndef DOUBLE_MAX
+#define DOUBLE_MAX 1.7976931348623157E+308 /* max decimal value of a "double"*/
+#endif
+#ifndef DOUBLE_MIN
+#define DOUBLE_MIN 2.2250738585072014E-308 /* min decimal value of a "double"*/
+#endif
+// NOLINTEND
+
 
 namespace Base
 {
diff --git a/src/Base/Tools3D.cpp b/src/Base/Tools3D.cpp
index 3cf103e96a..605759e2c9 100644
--- a/src/Base/Tools3D.cpp
+++ b/src/Base/Tools3D.cpp
@@ -23,13 +23,9 @@
 
 #include "PreCompiled.h"
 
-#ifndef _PreComp_
-#include <cstdlib>
-#include <set>
-#endif
-
+#include "BoundBox.h"
+#include "Placement.h"
 #include "Tools3D.h"
-#include "Vector3D.h"
 
 using namespace Base;
 
diff --git a/src/Base/Tools3D.h b/src/Base/Tools3D.h
index f8dfbe39c4..fb73839f4a 100644
--- a/src/Base/Tools3D.h
+++ b/src/Base/Tools3D.h
@@ -24,27 +24,27 @@
 #ifndef BASE_TOOLS3D_H
 #define BASE_TOOLS3D_H
 
-
-#include <algorithm>
-#include <cmath>
-#include <cfloat>
-#include <cstdio>
-#include <list>
-#include <vector>
-
-#include <Base/BoundBox.h>
-#include <Base/Placement.h>
 #ifndef FC_GLOBAL_H
 #include <FCGlobal.h>
 #endif
 
+#include <cmath>
+#include <vector>
+
 namespace Base
 {
-
-class Vector2d;
+template<typename T>
+class BoundBox3;
 class BoundBox2d;
 class Line2d;
+class Matrix4D;
 class Polygon2d;
+class Placement;
+class Rotation;
+template<typename T>
+class Vector3;
+using Vector3d = Vector3<double>;
+class Vector2d;
 
 /** Line3 ********************************************/
 
diff --git a/src/Base/Translate.h b/src/Base/Translate.h
index 57ec1c3cee..239dcb5f26 100644
--- a/src/Base/Translate.h
+++ b/src/Base/Translate.h
@@ -25,7 +25,6 @@
 #define BASE_TRANSLATE_H
 
 #include <CXX/Extensions.hxx>
-#include <CXX/Objects.hxx>
 #include <QTranslator>
 #include <memory>
 #include <list>
@@ -33,6 +32,11 @@
 #include <FCGlobal.h>
 #endif
 
+namespace Py
+{
+class Object;
+class Tuple;
+}  // namespace Py
 
 namespace Base
 {
diff --git a/src/Base/Type.cpp b/src/Base/Type.cpp
index f12c041aaf..421833305f 100644
--- a/src/Base/Type.cpp
+++ b/src/Base/Type.cpp
@@ -26,15 +26,12 @@
 #include <cassert>
 #endif
 
-/// Here the FreeCAD includes sorted by Base,App,Gui......
 #include "Type.h"
-#include "Exception.h"
 #include "Interpreter.h"
 #include "Console.h"
 
 
 using namespace Base;
-using namespace std;
 
 
 struct Base::TypeData
@@ -55,9 +52,9 @@ struct Base::TypeData
     Type::instantiationMethod instMethod;
 };
 
-map<string, unsigned int> Type::typemap;
-vector<TypeData*> Type::typedata;
-set<string> Type::loadModuleSet;
+std::map<std::string, unsigned int> Type::typemap;
+std::vector<TypeData*> Type::typedata;
+std::set<std::string> Type::loadModuleSet;
 
 void* Type::createInstance() const
 {
@@ -90,7 +87,7 @@ void* Type::createInstanceByName(const char* TypeName, bool bLoadModule)
 void Type::importModule(const char* TypeName)
 {
     // cut out the module name
-    const string mod = getModuleName(TypeName);
+    const std::string mod = getModuleName(TypeName);
 
     // ignore base modules
     if (mod == "App" || mod == "Gui" || mod == "Base") {
@@ -111,12 +108,13 @@ void Type::importModule(const char* TypeName)
     loadModuleSet.insert(mod);
 }
 
-string Type::getModuleName(const char* ClassName)
+std::string Type::getModuleName(const char* ClassName)
 {
-    string_view classNameView(ClassName);
+    std::string_view classNameView(ClassName);
     auto pos = classNameView.find("::");
 
-    return pos != string_view::npos ? string(classNameView.substr(0, pos)) : string();
+    return pos != std::string_view::npos ? std::string(classNameView.substr(0, pos))
+                                         : std::string();
 }
 
 Type Type::badType()
diff --git a/src/Base/TypePyImp.cpp b/src/Base/TypePyImp.cpp
index d8e9016407..c997bb69c4 100644
--- a/src/Base/TypePyImp.cpp
+++ b/src/Base/TypePyImp.cpp
@@ -24,7 +24,6 @@
 #include "PreCompiled.h"
 
 #include "Type.h"
-#include "BaseClassPy.h"
 #include "BindingManager.h"
 #include "TypePy.h"
 #include "TypePy.cpp"
diff --git a/src/Base/UniqueNameManager.cpp b/src/Base/UniqueNameManager.cpp
index c271ab3727..e2941ffb45 100644
--- a/src/Base/UniqueNameManager.cpp
+++ b/src/Base/UniqueNameManager.cpp
@@ -22,6 +22,7 @@
 
 #include "PreCompiled.h"
 #ifndef _PreComp_
+#include <algorithm>
 #include <tuple>
 #include <vector>
 #include <string>
diff --git a/src/Base/UniqueNameManager.h b/src/Base/UniqueNameManager.h
index 6db466d245..ee17a39be8 100644
--- a/src/Base/UniqueNameManager.h
+++ b/src/Base/UniqueNameManager.h
@@ -30,9 +30,7 @@
 #include <string>
 #include <set>
 #include <map>
-#include <algorithm>
-#include <utility>
-#include <tuple>
+#include <utility>  // Forward declares std::tuple
 
 // ----------------------------------------------------------------------------
 
diff --git a/src/Base/Unit.cpp b/src/Base/Unit.cpp
index 45a53dedb1..17a30adb44 100644
--- a/src/Base/Unit.cpp
+++ b/src/Base/Unit.cpp
@@ -28,7 +28,6 @@
 #include <cstring>
 #include <limits>
 #include <sstream>
-#include <utility>
 #endif
 
 #include "Unit.h"
diff --git a/src/Base/UnitsApi.cpp b/src/Base/UnitsApi.cpp
index 2cf7255200..0cf3133d0e 100644
--- a/src/Base/UnitsApi.cpp
+++ b/src/Base/UnitsApi.cpp
@@ -23,9 +23,8 @@
 
 #include "PreCompiled.h"
 
-#include <iostream>
+#include <sstream>
 #include <iomanip>
-#include <locale>
 #include <memory>
 
 #include <CXX/WrapPython.h>
diff --git a/src/Base/UnitsApi.h b/src/Base/UnitsApi.h
index 672526a43b..3a0b7e19f8 100644
--- a/src/Base/UnitsApi.h
+++ b/src/Base/UnitsApi.h
@@ -25,11 +25,13 @@
 #define BASE_UNITSAPI_H
 
 #include <memory>
-#include <QString>
 #include <QCoreApplication>
 #include "UnitsSchema.h"
 #include "Quantity.h"
 
+
+class QString;
+
 using PyObject = struct _object;
 using PyMethodDef = struct PyMethodDef;
 
diff --git a/src/Base/UnitsSchema.cpp b/src/Base/UnitsSchema.cpp
index 7d371017d2..bb544f3259 100644
--- a/src/Base/UnitsSchema.cpp
+++ b/src/Base/UnitsSchema.cpp
@@ -28,6 +28,7 @@
 #include <QLocale>
 #include <QString>
 
+#include "Quantity.h"
 #include "UnitsSchema.h"
 
 using namespace Base;
diff --git a/src/Base/UnitsSchema.h b/src/Base/UnitsSchema.h
index 1b7af446a0..117b46e86a 100644
--- a/src/Base/UnitsSchema.h
+++ b/src/Base/UnitsSchema.h
@@ -24,10 +24,10 @@
 #define BASE_UNITSSCHEMA_H
 
 #include <string>
-#include <Base/Quantity.h>
 
 namespace Base
 {
+class Quantity;
 
 /** Units systems */
 enum class UnitSystem
diff --git a/src/Base/UnitsSchemaCentimeters.cpp b/src/Base/UnitsSchemaCentimeters.cpp
index bd75f99fb7..f1b45119ca 100644
--- a/src/Base/UnitsSchemaCentimeters.cpp
+++ b/src/Base/UnitsSchemaCentimeters.cpp
@@ -25,9 +25,10 @@
 #ifndef _PreComp_
 #include <algorithm>
 #include <array>
-#include <utility>
 #endif
 
+#include "Quantity.h"
+#include "Unit.h"
 #include "UnitsSchemaCentimeters.h"
 
 using namespace Base;
diff --git a/src/Base/UnitsSchemaFemMilliMeterNewton.cpp b/src/Base/UnitsSchemaFemMilliMeterNewton.cpp
index 1f473c4d9d..602f825304 100644
--- a/src/Base/UnitsSchemaFemMilliMeterNewton.cpp
+++ b/src/Base/UnitsSchemaFemMilliMeterNewton.cpp
@@ -26,9 +26,10 @@
 #ifndef _PreComp_
 #include <algorithm>
 #include <array>
-#include <utility>
 #endif
 
+#include "Quantity.h"
+#include "Unit.h"
 #include "UnitsSchemaFemMilliMeterNewton.h"
 
 using namespace Base;
diff --git a/src/Base/UnitsSchemaImperial1.cpp b/src/Base/UnitsSchemaImperial1.cpp
index 4c6eef3417..49f36e322f 100644
--- a/src/Base/UnitsSchemaImperial1.cpp
+++ b/src/Base/UnitsSchemaImperial1.cpp
@@ -30,6 +30,7 @@
 #include <unistd.h>
 #endif
 
+#include "Quantity.h"
 #include "UnitsSchemaImperial1.h"
 
 using namespace Base;
diff --git a/src/Base/UnitsSchemaInternal.cpp b/src/Base/UnitsSchemaInternal.cpp
index 1d67455bab..4ef3fd217d 100644
--- a/src/Base/UnitsSchemaInternal.cpp
+++ b/src/Base/UnitsSchemaInternal.cpp
@@ -22,12 +22,17 @@
 
 
 #include "PreCompiled.h"
+#ifndef _PreComp_
+#include <cmath>
+#endif
 #ifdef __GNUC__
 #include <unistd.h>
 #endif
 
+
+#include "Quantity.h"
+#include "Unit.h"
 #include "UnitsSchemaInternal.h"
-#include <cmath>
 
 using namespace Base;
 
diff --git a/src/Base/UnitsSchemaMKS.cpp b/src/Base/UnitsSchemaMKS.cpp
index 241e3eba9b..0727c161c4 100644
--- a/src/Base/UnitsSchemaMKS.cpp
+++ b/src/Base/UnitsSchemaMKS.cpp
@@ -22,12 +22,16 @@
 
 
 #include "PreCompiled.h"
+#ifndef _PreComp_
+#include <cmath>
+#endif
 #ifdef __GNUC__
 #include <unistd.h>
 #endif
 
+#include "Quantity.h"
+#include "Unit.h"
 #include "UnitsSchemaMKS.h"
-#include <cmath>
 
 using namespace Base;
 
diff --git a/src/Base/UnitsSchemaMeterDecimal.cpp b/src/Base/UnitsSchemaMeterDecimal.cpp
index 8d7337bdac..52a6a9ca41 100644
--- a/src/Base/UnitsSchemaMeterDecimal.cpp
+++ b/src/Base/UnitsSchemaMeterDecimal.cpp
@@ -32,9 +32,10 @@
 #ifndef _PreComp_
 #include <algorithm>
 #include <array>
-#include <utility>
 #endif
 
+#include "Quantity.h"
+#include "Unit.h"
 #include "UnitsSchemaMeterDecimal.h"
 
 using namespace Base;
diff --git a/src/Base/UnitsSchemaMmMin.cpp b/src/Base/UnitsSchemaMmMin.cpp
index dece178cd1..ab7752a0c4 100644
--- a/src/Base/UnitsSchemaMmMin.cpp
+++ b/src/Base/UnitsSchemaMmMin.cpp
@@ -25,9 +25,10 @@
 #ifndef _PreComp_
 #include <algorithm>
 #include <array>
-#include <utility>
 #endif
 
+#include "Quantity.h"
+#include "Unit.h"
 #include "UnitsSchemaMmMin.h"
 
 using namespace Base;
diff --git a/src/Base/ViewProj.h b/src/Base/ViewProj.h
index b986447bc3..b1b31f4a1c 100644
--- a/src/Base/ViewProj.h
+++ b/src/Base/ViewProj.h
@@ -24,12 +24,15 @@
 #ifndef BASE_VIEWPROJ_H
 #define BASE_VIEWPROJ_H
 
-#include "Vector3D.h"
 #include "Matrix.h"
 
 
 namespace Base
 {
+template<typename T>
+class Vector3;
+using Vector3d = Vector3<double>;
+
 
 /**
  * Abstract base class for all project methods.
diff --git a/src/Base/Writer.cpp b/src/Base/Writer.cpp
index d80af5a743..91e67bbdb9 100644
--- a/src/Base/Writer.cpp
+++ b/src/Base/Writer.cpp
@@ -37,10 +37,9 @@
 #include "Tools.h"
 
 #include <boost/iostreams/filtering_stream.hpp>
+#include <zipios++/zipinputstream.h>
 
 using namespace Base;
-using namespace std;
-using namespace zipios;
 
 // boost iostream filter to escape ']]>' in text file saved into CDATA section.
 // It does not check if the character is valid utf8 or not.
@@ -146,7 +145,7 @@ void Writer::insertAsciiFile(const char* FileName)
     while (from.get(ch)) {
         Stream().put(ch);
     }
-    Stream() << "]]>" << endl;
+    Stream() << "]]>" << std::endl;
 }
 
 void Writer::insertBinFile(const char* FileName)
@@ -164,7 +163,7 @@ void Writer::insertBinFile(const char* FileName)
     // NOLINTNEXTLINE(cppcoreguidelines-pro-type-reinterpret-cast)
     from.read(reinterpret_cast<char*>(bytes.data()), fileSize);
     Stream() << Base::base64_encode(bytes.data(), static_cast<unsigned int>(fileSize));
-    Stream() << "]]>" << endl;
+    Stream() << "]]>" << std::endl;
 }
 
 void Writer::setForceXML(bool on)
@@ -336,7 +335,7 @@ ZipWriter::ZipWriter(const char* FileName)
     ZipStream.imbue(std::locale::classic());
 #endif
     ZipStream.precision(std::numeric_limits<double>::digits10 + 1);
-    ZipStream.setf(ios::fixed, ios::floatfield);
+    ZipStream.setf(std::ios::fixed, std::ios::floatfield);
 }
 
 ZipWriter::ZipWriter(std::ostream& os)
@@ -348,7 +347,7 @@ ZipWriter::ZipWriter(std::ostream& os)
     ZipStream.imbue(std::locale::classic());
 #endif
     ZipStream.precision(std::numeric_limits<double>::digits10 + 1);
-    ZipStream.setf(ios::fixed, ios::floatfield);
+    ZipStream.setf(std::ios::fixed, std::ios::floatfield);
 }
 
 void ZipWriter::putNextEntry(const char* file, const char* obj)
diff --git a/src/Base/Writer.h b/src/Base/Writer.h
index 5ca61be9df..15d8368768 100644
--- a/src/Base/Writer.h
+++ b/src/Base/Writer.h
@@ -28,16 +28,9 @@
 #include <string>
 #include <sstream>
 #include <vector>
-#include <cassert>
 #include <memory>
 
-#ifdef _MSC_VER
-#include <zipios++/zipios-config.h>
-#endif
-#include <zipios++/zipfile.h>
-#include <zipios++/zipinputstream.h>
 #include <zipios++/zipoutputstream.h>
-#include <zipios++/meta-iostreams.h>
 
 #include "FileInfo.h"
 
diff --git a/src/Base/XMLTools.cpp b/src/Base/XMLTools.cpp
index e1daf57a8b..7b6c911c99 100644
--- a/src/Base/XMLTools.cpp
+++ b/src/Base/XMLTools.cpp
@@ -23,9 +23,10 @@
 
 #include "PreCompiled.h"
 
+#include "Exception.h"
 #include "XMLTools.h"
 
-using namespace Base;
+
 #ifndef XERCES_CPP_NAMESPACE_BEGIN
 #define XERCES_CPP_NAMESPACE_QUALIFIER
 using namespace XERCES_CPP_NAMESPACE;
diff --git a/src/Base/XMLTools.h b/src/Base/XMLTools.h
index cc17d1b336..a8747c5b25 100644
--- a/src/Base/XMLTools.h
+++ b/src/Base/XMLTools.h
@@ -26,14 +26,11 @@
 #define BASE_XMLTOOLS_H
 
 #include <memory>
-#include <iostream>
+#include <ostream>
 #include <xercesc/util/TransService.hpp>
 
-#include <Base/Exception.h>
-
 #ifndef XERCES_CPP_NAMESPACE_BEGIN
 #define XERCES_CPP_NAMESPACE_QUALIFIER
-using namespace XERCES_CPP_NAMESPACE;
 namespace XERCES_CPP_NAMESPACE
 {
 class DOMNode;
diff --git a/src/Base/ZipHeader.cpp b/src/Base/ZipHeader.cpp
index b3273810d5..41e46a6bf1 100644
--- a/src/Base/ZipHeader.cpp
+++ b/src/Base/ZipHeader.cpp
@@ -24,6 +24,7 @@
 #include "PreCompiled.h"
 
 #include "ZipHeader.h"
+#include <zipios++/backbuffer.h>
 #include <zipios++/zipinputstream.h>
 
 using zipios::ConstEntryPointer;
diff --git a/src/Base/ZipHeader.h b/src/Base/ZipHeader.h
index 8c9e58dbe8..173e1e35f7 100644
--- a/src/Base/ZipHeader.h
+++ b/src/Base/ZipHeader.h
@@ -25,7 +25,8 @@
 #define ZIPIOS_ZIP_HEADER_H
 
 #include <FCGlobal.h>
-#include <zipios++/backbuffer.h>
+#include <zipios++/ziphead.h>
+#include <zipios++/virtualseeker.h>
 #include <zipios++/fcoll.h>
 
 namespace zipios
diff --git a/src/Gui/MergeDocuments.cpp b/src/Gui/MergeDocuments.cpp
index aeafb24704..c13daee0c5 100644
--- a/src/Gui/MergeDocuments.cpp
+++ b/src/Gui/MergeDocuments.cpp
@@ -25,6 +25,8 @@
 # include <stack>
 #endif
 
+#include <zipios++/zipinputstream.h>
+
 #include <App/Document.h>
 #include <App/DocumentObject.h>
 #include <Base/Reader.h>
diff --git a/src/Mod/Part/App/Geometry2d.cpp b/src/Mod/Part/App/Geometry2d.cpp
index 4095d4afb3..93f535fd79 100644
--- a/src/Mod/Part/App/Geometry2d.cpp
+++ b/src/Mod/Part/App/Geometry2d.cpp
@@ -59,6 +59,7 @@
 
 #include <Base/Exception.h>
 #include <Base/Reader.h>
+#include <Base/Vector3D.h>
 #include <Base/Writer.h>
 
 #include "Geometry2d.h"
diff --git a/src/Mod/Part/App/Services.cpp b/src/Mod/Part/App/Services.cpp
index 1c5446564f..9cc75b24d2 100644
--- a/src/Mod/Part/App/Services.cpp
+++ b/src/Mod/Part/App/Services.cpp
@@ -23,6 +23,8 @@
 
 #include "PreCompiled.h"
 
+#include <Base/Vector3D.h>
+
 #include "Services.h"
 
 AttacherSubObjectPlacement::AttacherSubObjectPlacement()
diff --git a/src/Mod/Part/Gui/TaskCheckGeometry.cpp b/src/Mod/Part/Gui/TaskCheckGeometry.cpp
index 378d3de02d..ec0e6e94ba 100644
--- a/src/Mod/Part/Gui/TaskCheckGeometry.cpp
+++ b/src/Mod/Part/Gui/TaskCheckGeometry.cpp
@@ -57,6 +57,7 @@
 #endif //_PreComp_
 
 #include <Base/Interpreter.h>
+#include <Base/TimeInfo.h>
 #include <Gui/Application.h>
 #include <Gui/BitmapFactory.h>
 #include <Gui/Document.h>
diff --git a/src/Mod/Start/App/DisplayedFilesModel.cpp b/src/Mod/Start/App/DisplayedFilesModel.cpp
index de3b3d1edf..1e1e2db79c 100644
--- a/src/Mod/Start/App/DisplayedFilesModel.cpp
+++ b/src/Mod/Start/App/DisplayedFilesModel.cpp
@@ -39,6 +39,7 @@
 #include <App/ProjectFile.h>
 #include <Base/FileInfo.h>
 #include <Base/Stream.h>
+#include <Base/TimeInfo.h>
 
 using namespace Start;
 
diff --git a/tests/src/Base/Axis.cpp b/tests/src/Base/Axis.cpp
index fc3bd39840..4124ea9261 100644
--- a/tests/src/Base/Axis.cpp
+++ b/tests/src/Base/Axis.cpp
@@ -1,5 +1,8 @@
 #include <gtest/gtest.h>
+
 #include <Base/Axis.h>
+#include <Base/Placement.h>
+#include <Base/Rotation.h>
 
 TEST(Axis, TestDefault)
 {
diff --git a/tests/src/Base/CoordinateSystem.cpp b/tests/src/Base/CoordinateSystem.cpp
index f97e8cc0c7..e779c7c88d 100644
--- a/tests/src/Base/CoordinateSystem.cpp
+++ b/tests/src/Base/CoordinateSystem.cpp
@@ -1,6 +1,7 @@
 #include <gtest/gtest.h>
 #include <Base/CoordinateSystem.h>
 #include <Base/Exception.h>
+#include <Base/Placement.h>
 
 // NOLINTBEGIN
 TEST(CoordinateSystem, TestDefault)
diff --git a/tests/src/Base/Tools3D.cpp b/tests/src/Base/Tools3D.cpp
index c04351a6fc..8e73109154 100644
--- a/tests/src/Base/Tools3D.cpp
+++ b/tests/src/Base/Tools3D.cpp
@@ -1,5 +1,6 @@
 #include <gtest/gtest.h>
 #include <Base/Tools3D.h>
+#include <Base/Vector3D.h>
 
 class Line3D: public ::testing::Test
 {