diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..89de354
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,17 @@
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
diff --git a/action.yml b/action.yml
index e8e67d2..a5d7182 100644
--- a/action.yml
+++ b/action.yml
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: MIT
 name: 'Forgejo release download and upload'
 author: 'Forgejo authors'
 description: |
diff --git a/forgejo-release.sh b/forgejo-release.sh
index a5201ac..f91ac50 100755
--- a/forgejo-release.sh
+++ b/forgejo-release.sh
@@ -1,4 +1,5 @@
 #!/bin/bash
+# SPDX-License-Identifier: MIT
 
 set -e
 
diff --git a/testdata/forgejo-release-test.sh b/testdata/forgejo-release-test.sh
index 49fcea2..946dfa0 100755
--- a/testdata/forgejo-release-test.sh
+++ b/testdata/forgejo-release-test.sh
@@ -1,4 +1,5 @@
 #!/bin/sh
+# SPDX-License-Identifier: MIT
 
 set -ex
 
diff --git a/testdata/nested-upload-download/.forgejo/workflows/test.yml b/testdata/nested-upload-download/.forgejo/workflows/test.yml
index 6757499..5fb1e3c 100644
--- a/testdata/nested-upload-download/.forgejo/workflows/test.yml
+++ b/testdata/nested-upload-download/.forgejo/workflows/test.yml
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: MIT
 name: Upload & Download a Forgejo Release
 on: [push]
 jobs: