diff --git a/.coveragerc b/.coveragerc
index 00c7903..980dc85 100644
--- a/.coveragerc
+++ b/.coveragerc
@@ -1,10 +1,5 @@
-# This file is part of Dictdiffer.
-#
-# Copyright (C) 2014 CERN.
-#
-# Dictdiffer is free software; you can redistribute it and/or modify
-# it under the terms of the MIT License; see LICENSE file for more
-# details.
+# SPDX-FileCopyrightText: 2014 CERN.
+# SPDX-License-Identifier: MIT
 
 [run]
 source = dictdiffer
diff --git a/.git-blame-ignore-revs b/.git-blame-ignore-revs
new file mode 100644
index 0000000..01c7707
--- /dev/null
+++ b/.git-blame-ignore-revs
@@ -0,0 +1 @@
+1c6111c7b0d1dbfcd0b0e2a1e2a2b9a4fb531277
diff --git a/.gitignore b/.gitignore
index 25d3399..3aca7a5 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,11 +1,6 @@
-# This file is part of Dictdiffer.
-#
-# Copyright (C) 2013 Fatih Erikli.
-# Copyright (C) 2014, 2016 CERN.
-#
-# Dictdiffer is free software; you can redistribute it and/or modify
-# it under the terms of the MIT License; see LICENSE file for more
-# details.
+# SPDX-FileCopyrightText: 2013 Fatih Erikli.
+# SPDX-FileCopyrightText: 2014, 2016 CERN.
+# SPDX-License-Identifier: MIT
 
 .eggs/
 *.egg
diff --git a/MANIFEST.in b/MANIFEST.in
index abed2b9..c6b08d7 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -1,11 +1,7 @@
-# This file is part of Dictdiffer.
-#
-# Copyright (C) 2014, 2016 CERN.
-#
-# Dictdiffer is free software; you can redistribute it and/or modify
-# it under the terms of the MIT License; see LICENSE file for more
-# details.
+# SPDX-FileCopyrightText: 2014, 2016 CERN.
+# SPDX-License-Identifier: MIT
 
+exclude .git-blame-ignore-revs
 include README.rst CHANGES CONTRIBUTING.rst AUTHORS LICENSE MANIFEST.in
 include RELEASE-NOTES.rst
 include .coveragerc pytest.ini
diff --git a/dictdiffer/__init__.py b/dictdiffer/__init__.py
index cbabf43..debd78a 100644
--- a/dictdiffer/__init__.py
+++ b/dictdiffer/__init__.py
@@ -1,12 +1,7 @@
-# This file is part of Dictdiffer.
-#
-# Copyright (C) 2013 Fatih Erikli.
-# Copyright (C) 2013, 2014, 2015, 2016 CERN.
-# Copyright (C) 2017-2019 ETH Zurich, Swiss Data Science Center, Jiri Kuncar.
-#
-# Dictdiffer is free software; you can redistribute it and/or modify
-# it under the terms of the MIT License; see LICENSE file for more
-# details.
+# SPDX-FileCopyrightText: 2013 Fatih Erikli.
+# SPDX-FileCopyrightText: 2013, 2014, 2015, 2016 CERN.
+# SPDX-FileCopyrightText: 2017-2019 ETH Zurich, Swiss Data Science Center, Jiri Kuncar.
+# SPDX-License-Identifier: MIT
 
 """Dictdiffer is a helper module to diff and patch dictionaries."""
 
diff --git a/dictdiffer/conflict.py b/dictdiffer/conflict.py
index 68b3425..0ad669e 100644
--- a/dictdiffer/conflict.py
+++ b/dictdiffer/conflict.py
@@ -1,10 +1,5 @@
-# This file is part of Dictdiffer.
-#
-# Copyright (C) 2015 CERN.
-#
-# Dictdiffer is free software; you can redistribute it and/or modify
-# it under the terms of the MIT License; see LICENSE file for more
-# details.
+# SPDX-FileCopyrightText: 2015 CERN.
+# SPDX-License-Identifier: MIT
 
 """Sub module to recognize conflicts in dictdiffer patches."""
 
diff --git a/dictdiffer/merge.py b/dictdiffer/merge.py
index 401ec1d..a8a8176 100644
--- a/dictdiffer/merge.py
+++ b/dictdiffer/merge.py
@@ -1,11 +1,6 @@
-# This file is part of Dictdiffer.
-#
-# Copyright (C) 2015 CERN.
-# Copyright (C) 2017 ETH Zurich, Swiss Data Science Center, Jiri Kuncar.
-#
-# Dictdiffer is free software; you can redistribute it and/or modify
-# it under the terms of the MIT License; see LICENSE file for more
-# details.
+# SPDX-FileCopyrightText: 2015 CERN.
+# SPDX-FileCopyrightText: 2017 ETH Zurich, Swiss Data Science Center, Jiri Kuncar.
+# SPDX-License-Identifier: MIT
 
 """Sub module to handle the merging of dictdiffer patches."""
 
diff --git a/dictdiffer/resolve.py b/dictdiffer/resolve.py
index 52bfc86..3396bf4 100644
--- a/dictdiffer/resolve.py
+++ b/dictdiffer/resolve.py
@@ -1,11 +1,6 @@
-# This file is part of Dictdiffer.
-#
-# Copyright (C) 2015 CERN.
-# Copyright (C) 2017 ETH Zurich, Swiss Data Science Center, Jiri Kuncar.
-#
-# Dictdiffer is free software; you can redistribute it and/or modify
-# it under the terms of the MIT License; see LICENSE file for more
-# details.
+# SPDX-FileCopyrightText: 2015 CERN.
+# SPDX-FileCopyrightText: 2017 ETH Zurich, Swiss Data Science Center, Jiri Kuncar.
+# SPDX-License-Identifier: MIT
 
 """Sub module to handle the conflict resolution."""
 
diff --git a/dictdiffer/testing.py b/dictdiffer/testing.py
index 142ff6b..68365b2 100644
--- a/dictdiffer/testing.py
+++ b/dictdiffer/testing.py
@@ -1,10 +1,5 @@
-# This file is part of Dictdiffer.
-#
-# Copyright (C) 2021 CERN.
-#
-# Dictdiffer is free software; you can redistribute it and/or modify
-# it under the terms of the MIT License; see LICENSE file for more
-# details.
+# SPDX-FileCopyrightText: 2021 CERN.
+# SPDX-License-Identifier: MIT
 """Define helper functions for testing."""
 
 from pprint import pformat
diff --git a/dictdiffer/unify.py b/dictdiffer/unify.py
index 6bac345..02e16fb 100644
--- a/dictdiffer/unify.py
+++ b/dictdiffer/unify.py
@@ -1,10 +1,5 @@
-# This file is part of Dictdiffer.
-#
-# Copyright (C) 2015 CERN.
-#
-# Dictdiffer is free software; you can redistribute it and/or modify
-# it under the terms of the MIT License; see LICENSE file for more
-# details.
+# SPDX-FileCopyrightText: 2015 CERN.
+# SPDX-License-Identifier: MIT
 
 """Sub module to handle the unification of patches after the merge."""
 
diff --git a/dictdiffer/utils.py b/dictdiffer/utils.py
index 5d59c92..3194f9f 100644
--- a/dictdiffer/utils.py
+++ b/dictdiffer/utils.py
@@ -1,11 +1,6 @@
-# This file is part of Dictdiffer.
-#
-# Copyright (C) 2015 CERN.
-# Copyright (C) 2017, 2019 ETH Zurich, Swiss Data Science Center, Jiri Kuncar.
-#
-# Dictdiffer is free software; you can redistribute it and/or modify
-# it under the terms of the MIT License; see LICENSE file for more
-# details.
+# SPDX-FileCopyrightText: 2015 CERN.
+# SPDX-FileCopyrightText: 2017, 2019 ETH Zurich, Swiss Data Science Center, Jiri Kuncar.
+# SPDX-License-Identifier: MIT
 
 """Utils gathers helper functions, classes for the dictdiffer module."""
 
diff --git a/dictdiffer/version.py b/dictdiffer/version.py
index 3149802..b1df833 100644
--- a/dictdiffer/version.py
+++ b/dictdiffer/version.py
@@ -1,4 +1,6 @@
-# -*- coding: utf-8 -*-
+# SPDX-FileCopyrightText: 2014-2021 CERN.
+# SPDX-License-Identifier: MIT
+
 # Do not change the format of this next line. Doing so risks breaking
 # setup.py and docs/conf.py
 """Version information for dictdiffer package."""
diff --git a/docs/Makefile b/docs/Makefile
index 100e568..f484f75 100644
--- a/docs/Makefile
+++ b/docs/Makefile
@@ -1,10 +1,5 @@
-# This file is part of Dictdiffer.
-#
-# Copyright (C) 2014 CERN.
-#
-# Dictdiffer is free software; you can redistribute it and/or modify
-# it under the terms of the MIT License; see LICENSE file for more
-# details.
+# SPDX-FileCopyrightText: 2014 CERN.
+# SPDX-License-Identifier: MIT
 
 # Makefile for Sphinx documentation
 #
diff --git a/docs/conf.py b/docs/conf.py
index 27f968b..4df8b04 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -1,12 +1,5 @@
-# -*- coding: utf-8 -*-
-#
-# This file is part of Dictdiffer.
-#
-# Copyright (C) 2014, 2016 CERN.
-#
-# Dictdiffer is free software; you can redistribute it and/or modify
-# it under the terms of the MIT License; see LICENSE file for more
-# details.
+# SPDX-FileCopyrightText: 2014, 2016 CERN.
+# SPDX-License-Identifier: MIT
 #
 # Dictdiffer documentation build configuration file, created by
 # sphinx-quickstart on Tue Aug 26 12:50:15 2014.
diff --git a/pytest.ini b/pytest.ini
index f9505b2..7f89147 100644
--- a/pytest.ini
+++ b/pytest.ini
@@ -1,10 +1,5 @@
-# This file is part of Dictdiffer.
-#
-# Copyright (C) 2014, 2016 CERN.
-#
-# Dictdiffer is free software; you can redistribute it and/or modify
-# it under the terms of the MIT License; see LICENSE file for more
-# details.
+# SPDX-FileCopyrightText: 2014, 2016 CERN.
+# SPDX-License-Identifier: MIT
 
 [pytest]
 addopts = --isort --pydocstyle --pycodestyle --doctest-glob="*.rst" --doctest-modules --cov=dictdiffer --cov-report=term-missing
diff --git a/run-tests.sh b/run-tests.sh
index 6ee1d8c..b360946 100755
--- a/run-tests.sh
+++ b/run-tests.sh
@@ -1,15 +1,8 @@
 #!/usr/bin/env bash
-# -*- coding: utf-8 -*-
-#
-# This file is part of Dictdiffer.
-#
-# Copyright (C) 2013 Fatih Erikli.
-# Copyright (C) 2014, 2016 CERN.
-# Copyright (C) 2019 ETH Zurich, Swiss Data Science Center, Jiri Kuncar.
-#
-# Dictdiffer is free software; you can redistribute it and/or modify
-# it under the terms of the MIT License; see LICENSE file for more
-# details.
+# SPDX-FileCopyrightText: 2013 Fatih Erikli.
+# SPDX-FileCopyrightText: 2014, 2016 CERN.
+# SPDX-FileCopyrightText: 2019 ETH Zurich, Swiss Data Science Center, Jiri Kuncar.
+# SPDX-License-Identifier: MIT
 
 # Quit on errors
 set -o errexit
diff --git a/setup.cfg b/setup.cfg
index 11a4e0f..05ddca3 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -1,10 +1,5 @@
-# This file is part of Dictdiffer.
-#
-# Copyright (C) 2016 CERN.
-#
-# Dictdiffer is free software; you can redistribute it and/or modify
-# it under the terms of the MIT License; see LICENSE file for more
-# details.
+# SPDX-FileCopyrightText: 2016 CERN.
+# SPDX-License-Identifier: MIT
 
 [aliases]
 test = pytest
diff --git a/setup.py b/setup.py
index 45e7baf..e7dd20a 100644
--- a/setup.py
+++ b/setup.py
@@ -1,12 +1,7 @@
-# This file is part of Dictdiffer.
-#
-# Copyright (C) 2013 Fatih Erikli.
-# Copyright (C) 2014, 2015, 2016 CERN.
-# Copyright (C) 2017, 2019 ETH Zurich, Swiss Data Science Center, Jiri Kuncar.
-#
-# Dictdiffer is free software; you can redistribute it and/or modify
-# it under the terms of the MIT License; see LICENSE file for more
-# details.
+# SPDX-FileCopyrightText: 2013 Fatih Erikli.
+# SPDX-FileCopyrightText: 2014, 2015, 2016 CERN.
+# SPDX-FileCopyrightText: 2017, 2019 ETH Zurich, Swiss Data Science Center, Jiri Kuncar.
+# SPDX-License-Identifier: MIT
 
 """Dictdiffer is a library that helps you to diff and patch dictionaries."""
 
diff --git a/tests/test_conflict.py b/tests/test_conflict.py
index 859d404..11a5a37 100644
--- a/tests/test_conflict.py
+++ b/tests/test_conflict.py
@@ -1,10 +1,5 @@
-# This file is part of Dictdiffer.
-#
-# Copyright (C) 2015 CERN.
-#
-# Dictdiffer is free software; you can redistribute it and/or modify
-# it under the terms of the MIT License; see LICENSE file for more
-# details.
+# SPDX-FileCopyrightText: 2015 CERN.
+# SPDX-License-Identifier: MIT
 
 import unittest
 
diff --git a/tests/test_dictdiffer.py b/tests/test_dictdiffer.py
index 0af3e3d..c1152b8 100644
--- a/tests/test_dictdiffer.py
+++ b/tests/test_dictdiffer.py
@@ -1,14 +1,7 @@
-# -*- coding: utf-8 -*-
-#
-# This file is part of Dictdiffer.
-#
-# Copyright (C) 2013 Fatih Erikli.
-# Copyright (C) 2013, 2014, 2015, 2016 CERN.
-# Copyright (C) 2017-2019 ETH Zurich, Swiss Data Science Center, Jiri Kuncar.
-#
-# Dictdiffer is free software; you can redistribute it and/or modify
-# it under the terms of the MIT License; see LICENSE file for more
-# details.
+# SPDX-FileCopyrightText: 2013 Fatih Erikli.
+# SPDX-FileCopyrightText: 2013, 2014, 2015, 2016 CERN.
+# SPDX-FileCopyrightText: 2017-2019 ETH Zurich, Swiss Data Science Center, Jiri Kuncar.
+# SPDX-License-Identifier: MIT
 
 import unittest
 from collections import OrderedDict
diff --git a/tests/test_merge.py b/tests/test_merge.py
index f1d8169..159c8f1 100644
--- a/tests/test_merge.py
+++ b/tests/test_merge.py
@@ -1,10 +1,5 @@
-# This file is part of Dictdiffer.
-#
-# Copyright (C) 2015 CERN.
-#
-# Dictdiffer is free software; you can redistribute it and/or modify
-# it under the terms of the MIT License; see LICENSE file for more
-# details.
+# SPDX-FileCopyrightText: 2015 CERN.
+# SPDX-License-Identifier: MIT
 
 import unittest
 
diff --git a/tests/test_resolve.py b/tests/test_resolve.py
index 2884c2d..9cc36c5 100644
--- a/tests/test_resolve.py
+++ b/tests/test_resolve.py
@@ -1,10 +1,5 @@
-# This file is part of Dictdiffer.
-#
-# Copyright (C) 2015 CERN.
-#
-# Dictdiffer is free software; you can redistribute it and/or modify
-# it under the terms of the MIT License; see LICENSE file for more
-# details.
+# SPDX-FileCopyrightText: 2015 CERN.
+# SPDX-License-Identifier: MIT
 
 import unittest
 
diff --git a/tests/test_testing.py b/tests/test_testing.py
index 2c23a82..056e9ae 100644
--- a/tests/test_testing.py
+++ b/tests/test_testing.py
@@ -1,10 +1,5 @@
-# This file is part of Dictdiffer.
-#
-# Copyright (C) 2021 CERN.
-#
-# Dictdiffer is free software; you can redistribute it and/or modify
-# it under the terms of the MIT License; see LICENSE file for more
-# details.
+# SPDX-FileCopyrightText: 2021 CERN.
+# SPDX-License-Identifier: MIT
 
 import unittest
 
diff --git a/tests/test_unify.py b/tests/test_unify.py
index 9e9c701..2663cd1 100644
--- a/tests/test_unify.py
+++ b/tests/test_unify.py
@@ -1,10 +1,5 @@
-# This file is part of Dictdiffer.
-#
-# Copyright (C) 2015 CERN.
-#
-# Dictdiffer is free software; you can redistribute it and/or modify
-# it under the terms of the MIT License; see LICENSE file for more
-# details.
+# SPDX-FileCopyrightText: 2015 CERN.
+# SPDX-License-Identifier: MIT
 
 import unittest
 
diff --git a/tests/test_utils.py b/tests/test_utils.py
index 591a7eb..8f9c444 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -1,10 +1,5 @@
-# This file is part of Dictdiffer.
-#
-# Copyright (C) 2015 CERN.
-#
-# Dictdiffer is free software; you can redistribute it and/or modify
-# it under the terms of the MIT License; see LICENSE file for more
-# details.
+# SPDX-FileCopyrightText: 2015 CERN.
+# SPDX-License-Identifier: MIT
 
 import unittest
 
diff --git a/tox.ini b/tox.ini
index f185675..f860c35 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,11 +1,6 @@
-# This file is part of Dictdiffer.
-#
-# Copyright (C) 2014 CERN.
-# Copyright (C) 2017 ETH Zurich, Swiss Data Science Center, Jiri Kuncar.
-#
-# Dictdiffer is free software; you can redistribute it and/or modify
-# it under the terms of the MIT License; see LICENSE file for more
-# details.
+# SPDX-FileCopyrightText: 2014 CERN.
+# SPDX-FileCopyrightText: 2017 ETH Zurich, Swiss Data Science Center, Jiri Kuncar.
+# SPDX-License-Identifier: MIT
 
 [tox]
 envlist = py35, py36, py37, py38, py39