diff --git a/bin/installexternal.py b/bin/installexternal.py
index 3fd7951bdc49c16ff1c26c4d568bb48252490d64..be197d4fa69250a9c39f7cc5e2c7fe9657abab9d 100755
--- a/bin/installexternal.py
+++ b/bin/installexternal.py
@@ -1,4 +1,10 @@
#!/usr/bin/env python3
+# SPDX-FileCopyrightInfo: Copyright © DuMux Project contributors, see AUTHORS.md in root folder
+# SPDX-License-Identifier: GPL-3.0-or-later
+# SPDX-FileCopyrightInfo: Copyright (c) 2020 Andrew Scott
+# SPDX-License-Identifier: MIT
+# The class TarSafe is adapted from https://github.com/beatsbears/tarsafe, licensed under MIT. All
+# Changes are licensed under GPL-3.0-or-later.
"""
install external stuff for dumux
diff --git a/doc/doxygen/doxygen-awesome-darkmode-toggle.js b/doc/doxygen/doxygen-awesome-darkmode-toggle.js
index 40fe2d38e090c2edffc04f5be214673b5dd309a8..9760307bc946aa94d5bd27e1cde67f415d31a98f 100644
--- a/doc/doxygen/doxygen-awesome-darkmode-toggle.js
+++ b/doc/doxygen/doxygen-awesome-darkmode-toggle.js
@@ -1,3 +1,5 @@
+// SPDX-FileCopyrightInfo: Copyright (c) 2021 - 2023 jothepro
+// SPDX-License-Identifier: MIT
/**
Doxygen Awesome
diff --git a/doc/doxygen/doxygen-awesome-fragment-copy-button.js b/doc/doxygen/doxygen-awesome-fragment-copy-button.js
index 86c16fd93a71686745a8c5568ac41a5d270a1b26..144c6b55faeba92fe324be8731ff20113a9e2b57 100644
--- a/doc/doxygen/doxygen-awesome-fragment-copy-button.js
+++ b/doc/doxygen/doxygen-awesome-fragment-copy-button.js
@@ -1,3 +1,5 @@
+// SPDX-FileCopyrightInfo: Copyright (c) 2022 - 2023 jothepro
+// SPDX-License-Identifier: MIT
/**
Doxygen Awesome
diff --git a/doc/doxygen/doxygen-awesome-interactive-toc.js b/doc/doxygen/doxygen-awesome-interactive-toc.js
index 20a9669d7df048e75464480c56500854c01fe881..906c7e2113cdc54ed05c374fbaffb9971017f19c 100644
--- a/doc/doxygen/doxygen-awesome-interactive-toc.js
+++ b/doc/doxygen/doxygen-awesome-interactive-toc.js
@@ -1,3 +1,5 @@
+// SPDX-FileCopyrightInfo: Copyright (c) 2022 - 2023 jothepro
+// SPDX-License-Identifier: MIT
/**
Doxygen Awesome
diff --git a/doc/doxygen/doxygen-awesome-paragraph-link.js b/doc/doxygen/doxygen-awesome-paragraph-link.js
index e53d132cea5abbc5a016e585c805f52ed715352c..71621059f09280ac80f72399e1ed490e8f30f0a2 100644
--- a/doc/doxygen/doxygen-awesome-paragraph-link.js
+++ b/doc/doxygen/doxygen-awesome-paragraph-link.js
@@ -1,3 +1,5 @@
+// SPDX-FileCopyrightInfo: Copyright (c) 2022 - 2023 jothepro
+// SPDX-License-Identifier: MIT
/**
Doxygen Awesome
diff --git a/doc/doxygen/doxygen-awesome-sidebar-only-darkmode-toggle.css b/doc/doxygen/doxygen-awesome-sidebar-only-darkmode-toggle.css
index d207446e0be8ca2f2129dc03e556f2678bf0abc8..21aa869dbebc6b598a6ece36292ff656d4a1967c 100644
--- a/doc/doxygen/doxygen-awesome-sidebar-only-darkmode-toggle.css
+++ b/doc/doxygen/doxygen-awesome-sidebar-only-darkmode-toggle.css
@@ -1,3 +1,5 @@
+/* SPDX-FileCopyrightInfo: Copyright (c) 2021 - 2023 jothepro */
+/* SPDX-License-Identifier: MIT */
/**
diff --git a/doc/doxygen/doxygen-awesome-sidebar-only.css b/doc/doxygen/doxygen-awesome-sidebar-only.css
index bab874b79119b47470178ccee4cb6f4472f6e0b3..6c4335e5635e937b07bbb4adc0a95881c6f38644 100644
--- a/doc/doxygen/doxygen-awesome-sidebar-only.css
+++ b/doc/doxygen/doxygen-awesome-sidebar-only.css
@@ -1,3 +1,5 @@
+/* SPDX-FileCopyrightInfo: Copyright (c) 2021 - 2023 jothepro */
+/* SPDX-License-Identifier: MIT */
/**
Doxygen Awesome
diff --git a/doc/doxygen/doxygen-awesome.css b/doc/doxygen/doxygen-awesome.css
index 41898d9a96efa2ffcea2a849f691a8897ac53a58..d9489388a643f179fd8e7e326fe4dffefac6f953 100644
--- a/doc/doxygen/doxygen-awesome.css
+++ b/doc/doxygen/doxygen-awesome.css
@@ -1,3 +1,5 @@
+/* SPDX-FileCopyrightInfo: Copyright (c) 2021 - 2023 jothepro */
+/* SPDX-License-Identifier: MIT */
/**
Doxygen Awesome
diff --git a/doc/doxygen/markdown-math-filter.pl b/doc/doxygen/markdown-math-filter.pl
index c764ff399d803189ba16c53a146066a5146a89a5..83bbee8358ae0ced15147e41b69e2c4fa8f515d6 100755
--- a/doc/doxygen/markdown-math-filter.pl
+++ b/doc/doxygen/markdown-math-filter.pl
@@ -1,4 +1,10 @@
#!/usr/bin/env perl
+# SPDX-FileCopyrightInfo: Copyright © DuMux Project contributors, see AUTHORS.md in root folder
+# SPDX-License-Identifier: GPL-3.0-or-later
+# SPDX-FileCopyrightInfo: Copyright 2017 - 2023 Simulating eXtreme Spacetimes Collaboration
+# SPDX-License-Identifier: MIT
+# Based on the original by Simulating eXtreme Spacetimes Collaboration,
+# licensed under MIT. All Changes are licensed under GPL-3.0-or-later.
#
#
# Doxygen filter to format markdown math for Doxygen
diff --git a/dumux/common/doubleexpintegrationconstants.hh b/dumux/common/doubleexpintegrationconstants.hh
index eb969e4845c30c2d64731b6e4fcff4153759d524..f53b416de9dde565a08b3c5f9d68ab8397f49720 100644
--- a/dumux/common/doubleexpintegrationconstants.hh
+++ b/dumux/common/doubleexpintegrationconstants.hh
@@ -1,5 +1,14 @@
// -*- mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
// vi: set et ts=4 sw=4 sts=4:
+//
+// SPDX-FileCopyrightInfo: Copyright © DuMux Project contributors, see AUTHORS.md in root folder
+// SPDX-License-Identifier: GPL-3.0-or-later
+// SPDX-FileCopyrightInfo: Copyright John D. Cook
+// SPDX-License-Identifier: BSD-2-Clause
+// Modified after the original version at
+// https://www.codeproject.com/Articles/31550/Fast-Numerical-Integration licensed under
+// BSD-2-Clause. All Changes are licensed under GPL-3.0-or-later.
+//
/*****************************************************************************
* See the file COPYING for full copying permissions. *
* *
diff --git a/dumux/common/doubleexpintegrator.hh b/dumux/common/doubleexpintegrator.hh
index 3591e82a01e9f538b0a1456af617dbb178489acf..5493698f4d8e959f507d749ee6f62d0d1b0019c0 100644
--- a/dumux/common/doubleexpintegrator.hh
+++ b/dumux/common/doubleexpintegrator.hh
@@ -1,5 +1,14 @@
// -*- mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
// vi: set et ts=4 sw=4 sts=4:
+//
+// SPDX-FileCopyrightInfo: Copyright © DuMux Project contributors, see AUTHORS.md in root folder
+// SPDX-License-Identifier: GPL-3.0-or-later
+// SPDX-FileCopyrightInfo: Copyright John D. Cook
+// SPDX-License-Identifier: BSD-2-Clause
+// Modified after the original version at
+// https://www.codeproject.com/Articles/31550/Fast-Numerical-Integration licensed under
+// BSD-2-Clause. All Changes are licensed under GPL-3.0-or-later.
+//
/*****************************************************************************
* See the file COPYING for full copying permissions. *
* *
diff --git a/dumux/io/format/fmt/README.rst b/dumux/io/format/fmt/README.rst
index 152ce16ebae536955bce4a6d124ed0bad26ac5e2..4c447f96c5dbf98483777b745bb51219617d8d13 100644
--- a/dumux/io/format/fmt/README.rst
+++ b/dumux/io/format/fmt/README.rst
@@ -1,3 +1,7 @@
+::
+ SPDX-FileCopyrightInfo: Copyright (c) 2012 - present, Victor Zverovich
+ SPDX-License-Identifier: LicenseRef-fmt
+
.. image:: https://user-images.githubusercontent.com/
576385/156254208-f5b743a9-88cf-439d-b0c0-923d53e8d551.png
:width: 25%
diff --git a/dumux/io/format/fmt/VERSION.rst b/dumux/io/format/fmt/VERSION.rst
index 47da986f86fdaed33e15cdc6431a1abf742e8398..9d0b8402f914537dc1cf1a63538d87c03e480c8c 100644
--- a/dumux/io/format/fmt/VERSION.rst
+++ b/dumux/io/format/fmt/VERSION.rst
@@ -1 +1,5 @@
+::
+ SPDX-FileCopyrightInfo: Copyright (c) 2012 - present, Victor Zverovich
+ SPDX-License-Identifier: LicenseRef-fmt
+
9.1.0
diff --git a/dumux/io/format/fmt/core.h b/dumux/io/format/fmt/core.h
index aa24b4cc44e3c2dcf46d5d7f7614a2177c02c557..16969a1bb796c9054cd1e45cc6b19f7b64324e64 100644
--- a/dumux/io/format/fmt/core.h
+++ b/dumux/io/format/fmt/core.h
@@ -1,3 +1,7 @@
+//
+// SPDX-FileCopyrightInfo: Copyright (c) 2012 - present, Victor Zverovich
+// SPDX-License-Identifier: LicenseRef-fmt
+//
// Formatting library for C++ - the core API for char/UTF-8
//
// Copyright (c) 2012 - present, Victor Zverovich
diff --git a/dumux/io/format/fmt/format-inl.h b/dumux/io/format/fmt/format-inl.h
index 73c7feb99f708565d90b1f9a5f21098cb09e86ea..94689e07a93fa6f3cda19a697002f443d639d564 100644
--- a/dumux/io/format/fmt/format-inl.h
+++ b/dumux/io/format/fmt/format-inl.h
@@ -1,3 +1,7 @@
+//
+// SPDX-FileCopyrightInfo: Copyright (c) 2012 - 2016, Victor Zverovich
+// SPDX-License-Identifier: LicenseRef-fmt
+//
// Formatting library for C++ - implementation
//
// Copyright (c) 2012 - 2016, Victor Zverovich
diff --git a/dumux/io/format/fmt/format.cc b/dumux/io/format/fmt/format.cc
index 76d287b617348f43d03282ec17632acc0555aaa3..95d367287e99c92a1a3607fcf19ecf4718895734 100644
--- a/dumux/io/format/fmt/format.cc
+++ b/dumux/io/format/fmt/format.cc
@@ -1,3 +1,7 @@
+//
+// SPDX-FileCopyrightInfo: Copyright (c) 2012 - 2016, Victor Zverovich
+// SPDX-License-Identifier: LicenseRef-fmt
+//
// Formatting library for C++
//
// Copyright (c) 2012 - 2016, Victor Zverovich
diff --git a/dumux/io/format/fmt/format.h b/dumux/io/format/fmt/format.h
index a40f92fe17557f146e743016c45fa313b163d073..80fac4cee1aaf99488ef293ba0c4f549ce39ea50 100644
--- a/dumux/io/format/fmt/format.h
+++ b/dumux/io/format/fmt/format.h
@@ -1,3 +1,7 @@
+//
+// SPDX-FileCopyrightInfo: Copyright (c) 2012 - present, Victor Zverovich
+// SPDX-License-Identifier: LicenseRef-fmt
+//
/*
Formatting library for C++
diff --git a/dumux/io/format/fmt/ranges.h b/dumux/io/format/fmt/ranges.h
index 886c3a414c638ab355950326386919bb68811ac8..5535cd38fc58b0b370a450d8677ad9074c1e2eeb 100644
--- a/dumux/io/format/fmt/ranges.h
+++ b/dumux/io/format/fmt/ranges.h
@@ -1,3 +1,8 @@
+//
+// SPDX-FileCopyrightInfo: Copyright (c) 2012 - present, Victor Zverovich
+// SPDX-FileCopyrightInfo: Copyright (c) 2018 - present, Remotion (Igor Schulz)
+// SPDX-License-Identifier: LicenseRef-fmt
+//
// Formatting library for C++ - experimental range support
//
// Copyright (c) 2012 - present, Victor Zverovich
diff --git a/dumux/io/xml/tinyxml2.cpp b/dumux/io/xml/tinyxml2.cpp
index 215ffa59ef4e9e96529b4b438c842034d49bc6e4..c8b118662830f5c2858e25f6ae2aacd4b76f8816 100644
--- a/dumux/io/xml/tinyxml2.cpp
+++ b/dumux/io/xml/tinyxml2.cpp
@@ -1,3 +1,5 @@
+// SPDX-FileCopyrightInfo: Copyright (c) Lee Thomason
+// SPDX-License-Identifier: Zlib
/*
Original code by Lee Thomason (www.grinninglizard.com)
diff --git a/dumux/io/xml/tinyxml2.h b/dumux/io/xml/tinyxml2.h
index e8ea49ec9ac3d1612402589e793ba1e336739cd5..6b3ee7c4d3d6339576bed6115da755124843317e 100644
--- a/dumux/io/xml/tinyxml2.h
+++ b/dumux/io/xml/tinyxml2.h
@@ -1,3 +1,7 @@
+//
+// SPDX-FileCopyrightInfo: Copyright (c) Lee Thomason
+// SPDX-License-Identifier: Zlib
+//
/*
Original code by Lee Thomason (www.grinninglizard.com)