diff --git a/.github/workflows/check-spdx-license-id.yml b/.github/workflows/check-spdx-license-id.yml
new file mode 100644
index 0000000000..6cd8bf60d5
--- /dev/null
+++ b/.github/workflows/check-spdx-license-id.yml
@@ -0,0 +1,75 @@
+name: Check SPDX-License-Identifier
+
+on:
+  push:
+    branches:
+      - master
+      - develop
+  pull_request:
+
+jobs:
+  check-spdx-license-id:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4.1.1
+      - name: Check
+        run: |
+          counter=0
+
+          search() {
+            local directory="$1"
+            find "$directory" -type f \
+              '(' \
+                -name "*.cjs" -and -not -name '*.config.cjs' -o \
+                -name "*.html" -o \
+                -name "*.js" -and -not -name '*.config.js' -o \
+                -name "*.mjs" -and -not -name '*.config.mjs' -o \
+                -name "*.scss" -o \
+                -name "*.ts" -and -not -name '*.config.ts' -o \
+                -name "*.vue" \
+              ')' -and \
+              -not -name '*eslint*'
+          }
+
+          check() {
+            local file="$1"
+            if ! (
+              grep -q "SPDX-FileCopyrightText: syuilo and misskey-project" "$file" ||
+              grep -q "SPDX-License-Identifier: AGPL-3.0-only" "$file"
+            ); then
+              echo "Missing: $file"
+              ((counter++))
+            fi
+          }
+
+          directories=(
+            "cypress/e2e"
+            "packages/backend/migration"
+            "packages/backend/src"
+            "packages/backend/test"
+            "packages/frontend/.storybook"
+            "packages/frontend/@types"
+            "packages/frontend/lib"
+            "packages/frontend/public"
+            "packages/frontend/src"
+            "packages/frontend/test"
+            "packages/misskey-bubble-game/src"
+            "packages/misskey-reversi/src"
+            "packages/sw/src"
+            "scripts"
+          )
+
+          for directory in "${directories[@]}"; do
+            for file in $(search $directory); do
+              check "$file"
+            done
+          done
+
+          if [ $counter -gt 0 ]; then
+            echo "SPDX-License-Identifier is missing in $counter files."
+            exit 1
+          else
+            echo "SPDX-License-Identifier is certainly described in all target files!"
+            exit 0
+          fi
diff --git a/cypress/e2e/basic.cy.js b/cypress/e2e/basic.cy.js
index 604241d13c..d2525e0a7d 100644
--- a/cypress/e2e/basic.cy.js
+++ b/cypress/e2e/basic.cy.js
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 describe('Before setup instance', () => {
 	beforeEach(() => {
 		cy.resetState();
diff --git a/cypress/e2e/router.cy.js b/cypress/e2e/router.cy.js
index 6de27be5f4..8d8fb3af31 100644
--- a/cypress/e2e/router.cy.js
+++ b/cypress/e2e/router.cy.js
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 describe('Router transition', () => {
 	describe('Redirect', () => {
 		// サーバの初期化。ルートのテストに関しては各describeごとに1度だけ実行で十分だと思う（使いまわした方が早い）
diff --git a/cypress/e2e/widgets.cy.js b/cypress/e2e/widgets.cy.js
index df6ec8357d..847801a69f 100644
--- a/cypress/e2e/widgets.cy.js
+++ b/cypress/e2e/widgets.cy.js
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 /* flaky
 describe('After user signed in', () => {
 	beforeEach(() => {
diff --git a/packages/backend/generate_api_json.js b/packages/backend/generate_api_json.js
index 4079b3bb0a..602ced1d75 100644
--- a/packages/backend/generate_api_json.js
+++ b/packages/backend/generate_api_json.js
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 import { loadConfig } from './built/config.js'
 import { genOpenapiSpec } from './built/server/api/openapi/gen-spec.js'
 import { writeFileSync } from "node:fs";
@@ -5,4 +10,4 @@ import { writeFileSync } from "node:fs";
 const config = loadConfig();
 const spec = genOpenapiSpec(config, true);
 
-writeFileSync('./built/api.json', JSON.stringify(spec), 'utf-8');
\ No newline at end of file
+writeFileSync('./built/api.json', JSON.stringify(spec), 'utf-8');
diff --git a/packages/backend/migration/1689325027964-UserBlacklistAnntena.js b/packages/backend/migration/1689325027964-UserBlacklistAnntena.js
index ce246b20f8..2dc7774493 100644
--- a/packages/backend/migration/1689325027964-UserBlacklistAnntena.js
+++ b/packages/backend/migration/1689325027964-UserBlacklistAnntena.js
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 export class UserBlacklistAnntena1689325027964 {
     name = 'UserBlacklistAnntena1689325027964'
 
diff --git a/packages/backend/migration/1690417561185-fix-renote-muting.js b/packages/backend/migration/1690417561185-fix-renote-muting.js
index 14150b0362..d9604ca26c 100644
--- a/packages/backend/migration/1690417561185-fix-renote-muting.js
+++ b/packages/backend/migration/1690417561185-fix-renote-muting.js
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 export class FixRenoteMuting1690417561185 {
     name = 'FixRenoteMuting1690417561185'
 
diff --git a/packages/backend/migration/1690417561186-ChangeCacheRemoteFilesDefault.js b/packages/backend/migration/1690417561186-ChangeCacheRemoteFilesDefault.js
index 7eda5debe5..9bccdb3bb5 100644
--- a/packages/backend/migration/1690417561186-ChangeCacheRemoteFilesDefault.js
+++ b/packages/backend/migration/1690417561186-ChangeCacheRemoteFilesDefault.js
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 export class ChangeCacheRemoteFilesDefault1690417561186 {
     name = 'ChangeCacheRemoteFilesDefault1690417561186'
 
diff --git a/packages/backend/migration/1690417561187-Fix.js b/packages/backend/migration/1690417561187-Fix.js
index e780e66d7b..7f1d62d68c 100644
--- a/packages/backend/migration/1690417561187-Fix.js
+++ b/packages/backend/migration/1690417561187-Fix.js
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 export class Fix1690417561187 {
     name = 'Fix1690417561187'
 
diff --git a/packages/backend/migration/1690569881926-user-2fa-backup-codes.js b/packages/backend/migration/1690569881926-user-2fa-backup-codes.js
index 2049df8ea2..a3ef8dcf08 100644
--- a/packages/backend/migration/1690569881926-user-2fa-backup-codes.js
+++ b/packages/backend/migration/1690569881926-user-2fa-backup-codes.js
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 export class User2faBackupCodes1690569881926 {
 	name = 'User2faBackupCodes1690569881926'
 
diff --git a/packages/backend/migration/1691649257651-refine-announcement.js b/packages/backend/migration/1691649257651-refine-announcement.js
index d8d63f3103..ac621155d5 100644
--- a/packages/backend/migration/1691649257651-refine-announcement.js
+++ b/packages/backend/migration/1691649257651-refine-announcement.js
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 export class RefineAnnouncement1691649257651 {
     name = 'RefineAnnouncement1691649257651'
 
diff --git a/packages/backend/migration/1691657412740-refine-announcement-2.js b/packages/backend/migration/1691657412740-refine-announcement-2.js
index 8791f99f44..67edf19659 100644
--- a/packages/backend/migration/1691657412740-refine-announcement-2.js
+++ b/packages/backend/migration/1691657412740-refine-announcement-2.js
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 export class RefineAnnouncement21691657412740 {
     name = 'RefineAnnouncement21691657412740'
 
diff --git a/packages/backend/migration/1695260774117-verified-links.js b/packages/backend/migration/1695260774117-verified-links.js
index 18e0571d81..64c8a9ad8f 100644
--- a/packages/backend/migration/1695260774117-verified-links.js
+++ b/packages/backend/migration/1695260774117-verified-links.js
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 export class VerifiedLinks1695260774117 {
     name = 'VerifiedLinks1695260774117'
 
diff --git a/packages/backend/migration/1695288787870-following-notify.js b/packages/backend/migration/1695288787870-following-notify.js
index e7e2194b15..b3f78d5f2a 100644
--- a/packages/backend/migration/1695288787870-following-notify.js
+++ b/packages/backend/migration/1695288787870-following-notify.js
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 export class FollowingNotify1695288787870 {
     name = 'FollowingNotify1695288787870'
 
diff --git a/packages/backend/migration/1695440131671-short-name.js b/packages/backend/migration/1695440131671-short-name.js
index 2c37297fc1..fdc256caf8 100644
--- a/packages/backend/migration/1695440131671-short-name.js
+++ b/packages/backend/migration/1695440131671-short-name.js
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 export class ShortName1695440131671 {
     name = 'ShortName1695440131671'
 
diff --git a/packages/backend/migration/1695605508898-mutingNotificationTypes.js b/packages/backend/migration/1695605508898-mutingNotificationTypes.js
index 8c0e52a2f0..67d4243142 100644
--- a/packages/backend/migration/1695605508898-mutingNotificationTypes.js
+++ b/packages/backend/migration/1695605508898-mutingNotificationTypes.js
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 export class MutingNotificationTypes1695605508898 {
     name = 'MutingNotificationTypes1695605508898'
 
diff --git a/packages/backend/migration/1695901659683-note-updated-at.js b/packages/backend/migration/1695901659683-note-updated-at.js
index d8a151a1f7..e828fb1a6f 100644
--- a/packages/backend/migration/1695901659683-note-updated-at.js
+++ b/packages/backend/migration/1695901659683-note-updated-at.js
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 export class NoteUpdatedAt1695901659683 {
     name = 'NoteUpdatedAt1695901659683'
 
diff --git a/packages/backend/migration/1696323464251-user-list-membership.js b/packages/backend/migration/1696323464251-user-list-membership.js
index 7534040c4c..dc1d438dd7 100644
--- a/packages/backend/migration/1696323464251-user-list-membership.js
+++ b/packages/backend/migration/1696323464251-user-list-membership.js
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 export class UserListMembership1696323464251 {
     name = 'UserListMembership1696323464251'
 
diff --git a/packages/backend/migration/1696331570827-hibernation.js b/packages/backend/migration/1696331570827-hibernation.js
index 119d35913f..1487ece77c 100644
--- a/packages/backend/migration/1696331570827-hibernation.js
+++ b/packages/backend/migration/1696331570827-hibernation.js
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 export class Hibernation1696331570827 {
     name = 'Hibernation1696331570827'
 
diff --git a/packages/backend/migration/1696332072038-clean.js b/packages/backend/migration/1696332072038-clean.js
index 97dba655f4..92a6810d6a 100644
--- a/packages/backend/migration/1696332072038-clean.js
+++ b/packages/backend/migration/1696332072038-clean.js
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 export class Clean1696332072038 {
     name = 'Clean1696332072038'
 
diff --git a/packages/backend/migration/1700383825690-hard-mute.js b/packages/backend/migration/1700383825690-hard-mute.js
index afd3247f5c..92c3ada4a1 100644
--- a/packages/backend/migration/1700383825690-hard-mute.js
+++ b/packages/backend/migration/1700383825690-hard-mute.js
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 export class HardMute1700383825690 {
     name = 'HardMute1700383825690'
 
diff --git a/packages/backend/src/core/ChannelFollowingService.ts b/packages/backend/src/core/ChannelFollowingService.ts
index 75843b9773..12251595e2 100644
--- a/packages/backend/src/core/ChannelFollowingService.ts
+++ b/packages/backend/src/core/ChannelFollowingService.ts
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 import { Inject, Injectable, OnModuleInit } from '@nestjs/common';
 import Redis from 'ioredis';
 import { DI } from '@/di-symbols.js';
diff --git a/packages/backend/src/misc/fastify-hook-handlers.ts b/packages/backend/src/misc/fastify-hook-handlers.ts
index 49a48f6a6b..3e1c099e00 100644
--- a/packages/backend/src/misc/fastify-hook-handlers.ts
+++ b/packages/backend/src/misc/fastify-hook-handlers.ts
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 import type { onRequestHookHandler } from 'fastify';
 
 export const handleRequestRedirectToOmitSearch: onRequestHookHandler = (request, reply, done) => {
diff --git a/packages/backend/src/misc/is-pure-renote.ts b/packages/backend/src/misc/is-pure-renote.ts
index 994d981522..f9c2243a06 100644
--- a/packages/backend/src/misc/is-pure-renote.ts
+++ b/packages/backend/src/misc/is-pure-renote.ts
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 import type { MiNote } from '@/models/Note.js';
 
 export function isPureRenote(note: MiNote): note is MiNote & { renoteId: NonNullable<MiNote['renoteId']> } {
diff --git a/packages/backend/src/misc/loader.ts b/packages/backend/src/misc/loader.ts
index 25f7b54d31..7f29b9db10 100644
--- a/packages/backend/src/misc/loader.ts
+++ b/packages/backend/src/misc/loader.ts
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 export type FetchFunction<K, V> = (key: K) => Promise<V>;
 
 type ResolveReject<V> = Parameters<ConstructorParameters<typeof Promise<V>>[0]>;
diff --git a/packages/backend/src/models/ReversiGame.ts b/packages/backend/src/models/ReversiGame.ts
index c03335dd63..6b29a0ce8c 100644
--- a/packages/backend/src/models/ReversiGame.ts
+++ b/packages/backend/src/models/ReversiGame.ts
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 import { PrimaryColumn, Entity, Index, JoinColumn, Column, ManyToOne } from 'typeorm';
 import { id } from './util/id.js';
 import { MiUser } from './User.js';
diff --git a/packages/backend/src/models/json-schema/signin.ts b/packages/backend/src/models/json-schema/signin.ts
index d27d2490c5..45732a742b 100644
--- a/packages/backend/src/models/json-schema/signin.ts
+++ b/packages/backend/src/models/json-schema/signin.ts
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 export const packedSigninSchema = {
 	type: 'object',
 	properties: {
diff --git a/packages/backend/test/jest.setup.ts b/packages/backend/test/jest.setup.ts
index cf5b9bf24d..861bc6db66 100644
--- a/packages/backend/test/jest.setup.ts
+++ b/packages/backend/test/jest.setup.ts
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 import { initTestDb, sendEnvResetRequest } from './utils.js';
 
 beforeAll(async () => {
diff --git a/packages/backend/test/unit/ApMfmService.ts b/packages/backend/test/unit/ApMfmService.ts
index 2b79041c86..79cb81f5c9 100644
--- a/packages/backend/test/unit/ApMfmService.ts
+++ b/packages/backend/test/unit/ApMfmService.ts
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 import * as assert from 'assert';
 import { Test } from '@nestjs/testing';
 
diff --git a/packages/backend/test/unit/misc/loader.ts b/packages/backend/test/unit/misc/loader.ts
index fa37950951..2cf54e1555 100644
--- a/packages/backend/test/unit/misc/loader.ts
+++ b/packages/backend/test/unit/misc/loader.ts
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 import { DebounceLoader } from '@/misc/loader.js';
 
 class Mock {
diff --git a/packages/frontend/.storybook/preview-head.html b/packages/frontend/.storybook/preview-head.html
index 30f3ebfb64..e50c488243 100644
--- a/packages/frontend/.storybook/preview-head.html
+++ b/packages/frontend/.storybook/preview-head.html
@@ -1,3 +1,8 @@
+<!--
+SPDX-FileCopyrightText: syuilo and misskey-project
+SPDX-License-Identifier: AGPL-3.0-only
+-->
+
 <link rel="preload" href="https://github.com/misskey-dev/misskey/blob/master/packages/frontend/assets/about-icon.png?raw=true" as="image" type="image/png" crossorigin="anonymous">
 <link rel="preload" href="https://github.com/misskey-dev/misskey/blob/master/packages/frontend/assets/fedi.jpg?raw=true" as="image" type="image/jpeg" crossorigin="anonymous">
 <link rel="stylesheet" href="https://unpkg.com/@tabler/icons-webfont@2.44.0/tabler-icons.min.css">
diff --git a/packages/frontend/src/components/global/I18n.vue b/packages/frontend/src/components/global/I18n.vue
index 162aa2bcf8..6b7723e6ac 100644
--- a/packages/frontend/src/components/global/I18n.vue
+++ b/packages/frontend/src/components/global/I18n.vue
@@ -1,3 +1,8 @@
+<!--
+SPDX-FileCopyrightText: syuilo and misskey-project
+SPDX-License-Identifier: AGPL-3.0-only
+-->
+
 <template>
 <render/>
 </template>
diff --git a/packages/frontend/src/filters/kmg.ts b/packages/frontend/src/filters/kmg.ts
index 4dcb5c5800..9608e420f6 100644
--- a/packages/frontend/src/filters/kmg.ts
+++ b/packages/frontend/src/filters/kmg.ts
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 export default (v, fractionDigits = 0) => {
 	if (v == null) return 'N/A';
 	if (v === 0) return '0';
diff --git a/packages/frontend/src/scripts/check-reaction-permissions.ts b/packages/frontend/src/scripts/check-reaction-permissions.ts
index e7b473dd75..8fc857f84f 100644
--- a/packages/frontend/src/scripts/check-reaction-permissions.ts
+++ b/packages/frontend/src/scripts/check-reaction-permissions.ts
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 import * as Misskey from 'misskey-js';
 import { UnicodeEmojiDef } from './emojilist.js';
 
diff --git a/packages/frontend/src/scripts/clear-cache.ts b/packages/frontend/src/scripts/clear-cache.ts
index b20109ec72..71d1232710 100644
--- a/packages/frontend/src/scripts/clear-cache.ts
+++ b/packages/frontend/src/scripts/clear-cache.ts
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 import { unisonReload } from '@/scripts/unison-reload.js';
 import * as os from '@/os.js';
 import { miLocalStorage } from '@/local-storage.js';
diff --git a/packages/frontend/src/scripts/code-highlighter.ts b/packages/frontend/src/scripts/code-highlighter.ts
index 2733897bab..5dd0a3be78 100644
--- a/packages/frontend/src/scripts/code-highlighter.ts
+++ b/packages/frontend/src/scripts/code-highlighter.ts
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 import { bundledThemesInfo } from 'shiki';
 import { getHighlighterCore, loadWasm } from 'shiki/core';
 import darkPlus from 'shiki/themes/dark-plus.mjs';
diff --git a/packages/frontend/src/scripts/media-has-audio.ts b/packages/frontend/src/scripts/media-has-audio.ts
index 3421a38a76..4bf3ee5d97 100644
--- a/packages/frontend/src/scripts/media-has-audio.ts
+++ b/packages/frontend/src/scripts/media-has-audio.ts
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 export default async function hasAudio(media: HTMLMediaElement) {
 	const cloned = media.cloneNode() as HTMLMediaElement;
 	cloned.muted = (cloned as typeof cloned & Partial<HTMLVideoElement>).playsInline = true;
diff --git a/packages/frontend/src/type.ts b/packages/frontend/src/type.ts
index 9c0fc2a11e..5ff27158d2 100644
--- a/packages/frontend/src/type.ts
+++ b/packages/frontend/src/type.ts
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 export type WithRequired<T, K extends keyof T> = T & { [P in K]-?: T[P] };
 
 export type WithNonNullable<T, K extends keyof T> = T & { [P in K]-?: NonNullable<T[P]> };
diff --git a/scripts/changelog-checker/src/checker.ts b/scripts/changelog-checker/src/checker.ts
index bbd5b2270a..8fd6ff5629 100644
--- a/scripts/changelog-checker/src/checker.ts
+++ b/scripts/changelog-checker/src/checker.ts
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 import { Release } from './parser.js';
 
 export class Result {
diff --git a/scripts/changelog-checker/src/index.ts b/scripts/changelog-checker/src/index.ts
index 8cbeb297d9..0e2c5ce057 100644
--- a/scripts/changelog-checker/src/index.ts
+++ b/scripts/changelog-checker/src/index.ts
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 import * as process from 'process';
 import * as fs from 'fs';
 import { parseChangeLog } from './parser.js';
diff --git a/scripts/changelog-checker/src/parser.ts b/scripts/changelog-checker/src/parser.ts
index d6a9ddeda8..894d60d6af 100644
--- a/scripts/changelog-checker/src/parser.ts
+++ b/scripts/changelog-checker/src/parser.ts
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 import * as fs from 'node:fs';
 import { unified } from 'unified';
 import remarkParse from 'remark-parse';
diff --git a/scripts/changelog-checker/test/checker.test.ts b/scripts/changelog-checker/test/checker.test.ts
index bc73e5622b..9ca8fa85f2 100644
--- a/scripts/changelog-checker/test/checker.test.ts
+++ b/scripts/changelog-checker/test/checker.test.ts
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 import {expect, suite, test} from "vitest";
 import {Release, ReleaseCategory} from "../src/parser";
 import {checkNewRelease, checkNewTopic} from "../src/checker";
@@ -411,4 +416,4 @@ suite('checkNewTopic', () => {
 		console.log(result.message)
 		expect(result.success).toBe(false)
 	})
-})
\ No newline at end of file
+})
diff --git a/scripts/tarball.mjs b/scripts/tarball.mjs
index 936a43d270..b1862ad289 100644
--- a/scripts/tarball.mjs
+++ b/scripts/tarball.mjs
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 import { createWriteStream } from 'node:fs';
 import { mkdir } from 'node:fs/promises';
 import { resolve } from 'node:path';