diff --git a/.config/example.yml b/.config/example.yml
index 8fe41da15a619e7a9ca7cc31917134aef8b9736e..a19b5d04e826a2103b366976cde7debe624ad6b3 100644
--- a/.config/example.yml
+++ b/.config/example.yml
@@ -130,6 +130,7 @@ proxyBypassHosts:
 #proxySmtp: socks5://127.0.0.1:1080 # use SOCKS5
 
 # Media Proxy
+# Reference Implementation: https://github.com/misskey-dev/media-proxy
 #mediaProxy: https://example.com/proxy
 
 # Proxy remote files (default: false)
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1e10edf68351f9366643ee5c2885fe3f963ba93e..0ad1e36213455b1af7b4e5c7652afd93bb55fc72 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -24,6 +24,9 @@ You should also include the user name that made the change.
 - syslogのサポートが削除されました
 
 ### Improvements
+- 外部メディアプロキシへの対応を強化しました  
+  外部メディアプロキシのFastify実装を作りました  
+  https://github.com/misskey-dev/media-proxy
 - ロールで広告の非表示が有効になっている場合は最初から広告を非表示にするように
 
 ## 13.2.6 (2023/02/01)
diff --git a/packages/backend/src/config.ts b/packages/backend/src/config.ts
index 1d4e700656a7d3336f8ff88de961b5c3c61da37e..aa98ef1d22d2647a850635a5ecd1fdf55c965494 100644
--- a/packages/backend/src/config.ts
+++ b/packages/backend/src/config.ts
@@ -87,6 +87,8 @@ export type Mixin = {
 	userAgent: string;
 	clientEntry: string;
 	clientManifestExists: boolean;
+	mediaProxy: string;
+	externalMediaProxyEnabled: boolean;
 };
 
 export type Config = Source & Mixin;
@@ -135,6 +137,13 @@ export function loadConfig() {
 	mixin.clientEntry = clientManifest['src/init.ts'];
 	mixin.clientManifestExists = clientManifestExists;
 
+	const externalMediaProxy = config.mediaProxy ?
+		config.mediaProxy.endsWith('/') ? config.mediaProxy.substring(0, config.mediaProxy.length - 1) : config.mediaProxy
+		: null;
+	const internalMediaProxy = `${mixin.scheme}://${mixin.host}/proxy`;
+	mixin.mediaProxy = externalMediaProxy ?? internalMediaProxy;
+	mixin.externalMediaProxyEnabled = externalMediaProxy !== null && externalMediaProxy !== internalMediaProxy;
+
 	if (!config.redis.prefix) config.redis.prefix = mixin.host;
 
 	return Object.assign(config, mixin);
diff --git a/packages/backend/src/core/CustomEmojiService.ts b/packages/backend/src/core/CustomEmojiService.ts
index 39814e1be68e5bd1cfbb12db9eab249ce98141ed..63f0319442f57a53661de88c910a90acbd67f626 100644
--- a/packages/backend/src/core/CustomEmojiService.ts
+++ b/packages/backend/src/core/CustomEmojiService.ts
@@ -120,7 +120,7 @@ export class CustomEmojiService {
 		const url = isLocal
 			? emojiUrl
 			: this.config.proxyRemoteFiles
-				? `${this.config.url}/proxy/${encodeURIComponent((new URL(emojiUrl)).pathname)}?${query({ url: emojiUrl })}`
+				? `${this.config.mediaProxy}/emoji.webp?${query({ url: emojiUrl })}`
 				: emojiUrl;
 
 		return url;
diff --git a/packages/backend/src/core/entities/ChannelEntityService.ts b/packages/backend/src/core/entities/ChannelEntityService.ts
index 5e2f019a123b4218ec7cab7e92272c4520965a31..6ce590aa96a30b2413c2f6b82be8763cc9e6e124 100644
--- a/packages/backend/src/core/entities/ChannelEntityService.ts
+++ b/packages/backend/src/core/entities/ChannelEntityService.ts
@@ -54,7 +54,7 @@ export class ChannelEntityService {
 			name: channel.name,
 			description: channel.description,
 			userId: channel.userId,
-			bannerUrl: banner ? this.driveFileEntityService.getPublicUrl(banner, false) : null,
+			bannerUrl: banner ? this.driveFileEntityService.getPublicUrl(banner) : null,
 			usersCount: channel.usersCount,
 			notesCount: channel.notesCount,
 
diff --git a/packages/backend/src/core/entities/DriveFileEntityService.ts b/packages/backend/src/core/entities/DriveFileEntityService.ts
index 7f54cfdeaca0462b5bb187f97bad708637300e9f..efc196f74ab4d48885336b27c715d4422aa3948a 100644
--- a/packages/backend/src/core/entities/DriveFileEntityService.ts
+++ b/packages/backend/src/core/entities/DriveFileEntityService.ts
@@ -71,27 +71,41 @@ export class DriveFileEntityService {
 	}
 
 	@bindThis
-	public getPublicUrl(file: DriveFile, thumbnail = false): string | null {
+	public getPublicUrl(file: DriveFile, mode? : 'static' | 'avatar'): string | null { // static = thumbnail
+		const proxiedUrl = (url: string) => appendQuery(
+			`${this.config.mediaProxy}/${mode ?? 'image'}.webp`,
+			query({
+				url,
+				...(mode ? { [mode]: '1' } : {}),
+			})
+		);
+
 		// リモートかつメディアプロキシ
-		if (file.uri != null && file.userHost != null && this.config.mediaProxy != null) {
-			return appendQuery(this.config.mediaProxy, query({
-				url: file.uri,
-				thumbnail: thumbnail ? '1' : undefined,
-			}));
+		if (file.uri != null && file.userHost != null && this.config.externalMediaProxyEnabled) {
+			return proxiedUrl(file.uri);
 		}
 
 		// リモートかつ期限切れはローカルプロキシを試みる
 		if (file.uri != null && file.isLink && this.config.proxyRemoteFiles) {
-			const key = thumbnail ? file.thumbnailAccessKey : file.webpublicAccessKey;
+			const key = mode === 'static' ? file.thumbnailAccessKey : file.webpublicAccessKey;
 
 			if (key && !key.match('/')) {	// 古いものはここにオブジェクトストレージキーが入ってるので除外
-				return `${this.config.url}/files/${key}`;
+				const url = `${this.config.url}/files/${key}`;
+				if (mode === 'avatar') return proxiedUrl(url);
+				return url;
 			}
 		}
 
 		const isImage = file.type && ['image/png', 'image/apng', 'image/gif', 'image/jpeg', 'image/webp', 'image/avif', 'image/svg+xml'].includes(file.type);
 
-		return thumbnail ? (file.thumbnailUrl ?? (isImage ? (file.webpublicUrl ?? file.url) : null)) : (file.webpublicUrl ?? file.url);
+		if (mode === 'static') {
+			return file.thumbnailUrl ?? (isImage ? (file.webpublicUrl ?? file.url) : null);
+		}
+
+		const url = file.webpublicUrl ?? file.url;
+
+		if (mode === 'avatar') return proxiedUrl(url);
+		return url;
 	}
 
 	@bindThis
@@ -166,8 +180,8 @@ export class DriveFileEntityService {
 			isSensitive: file.isSensitive,
 			blurhash: file.blurhash,
 			properties: opts.self ? file.properties : this.getPublicProperties(file),
-			url: opts.self ? file.url : this.getPublicUrl(file, false),
-			thumbnailUrl: this.getPublicUrl(file, true),
+			url: opts.self ? file.url : this.getPublicUrl(file),
+			thumbnailUrl: this.getPublicUrl(file, 'static'),
 			comment: file.comment,
 			folderId: file.folderId,
 			folder: opts.detail && file.folderId ? this.driveFolderEntityService.pack(file.folderId, {
@@ -201,8 +215,8 @@ export class DriveFileEntityService {
 			isSensitive: file.isSensitive,
 			blurhash: file.blurhash,
 			properties: opts.self ? file.properties : this.getPublicProperties(file),
-			url: opts.self ? file.url : this.getPublicUrl(file, false),
-			thumbnailUrl: this.getPublicUrl(file, true),
+			url: opts.self ? file.url : this.getPublicUrl(file),
+			thumbnailUrl: this.getPublicUrl(file, 'static'),
 			comment: file.comment,
 			folderId: file.folderId,
 			folder: opts.detail && file.folderId ? this.driveFolderEntityService.pack(file.folderId, {
diff --git a/packages/backend/src/core/entities/UserEntityService.ts b/packages/backend/src/core/entities/UserEntityService.ts
index aaa80033b3f36a2bc26f7142b5f6ac903ed254f5..ff42c0735957f0e7fb1ae2a7d94c1d8033e0926b 100644
--- a/packages/backend/src/core/entities/UserEntityService.ts
+++ b/packages/backend/src/core/entities/UserEntityService.ts
@@ -314,10 +314,10 @@ export class UserEntityService implements OnModuleInit {
 	@bindThis
 	public async getAvatarUrl(user: User): Promise<string> {
 		if (user.avatar) {
-			return this.driveFileEntityService.getPublicUrl(user.avatar, true) ?? this.getIdenticonUrl(user.id);
+			return this.driveFileEntityService.getPublicUrl(user.avatar, 'avatar') ?? this.getIdenticonUrl(user.id);
 		} else if (user.avatarId) {
 			const avatar = await this.driveFilesRepository.findOneByOrFail({ id: user.avatarId });
-			return this.driveFileEntityService.getPublicUrl(avatar, true) ?? this.getIdenticonUrl(user.id);
+			return this.driveFileEntityService.getPublicUrl(avatar, 'avatar') ?? this.getIdenticonUrl(user.id);
 		} else {
 			return this.getIdenticonUrl(user.id);
 		}
@@ -326,7 +326,7 @@ export class UserEntityService implements OnModuleInit {
 	@bindThis
 	public getAvatarUrlSync(user: User): string {
 		if (user.avatar) {
-			return this.driveFileEntityService.getPublicUrl(user.avatar, true) ?? this.getIdenticonUrl(user.id);
+			return this.driveFileEntityService.getPublicUrl(user.avatar, 'avatar') ?? this.getIdenticonUrl(user.id);
 		} else {
 			return this.getIdenticonUrl(user.id);
 		}
@@ -422,7 +422,7 @@ export class UserEntityService implements OnModuleInit {
 				createdAt: user.createdAt.toISOString(),
 				updatedAt: user.updatedAt ? user.updatedAt.toISOString() : null,
 				lastFetchedAt: user.lastFetchedAt ? user.lastFetchedAt.toISOString() : null,
-				bannerUrl: user.banner ? this.driveFileEntityService.getPublicUrl(user.banner, false) : null,
+				bannerUrl: user.banner ? this.driveFileEntityService.getPublicUrl(user.banner) : null,
 				bannerBlurhash: user.banner?.blurhash ?? null,
 				isLocked: user.isLocked,
 				isSilenced: this.roleService.getUserPolicies(user.id).then(r => !r.canPublicNote),
diff --git a/packages/backend/src/server/FileServerService.ts b/packages/backend/src/server/FileServerService.ts
index 40024270ae1f56d78935589af708a5bb2d4f3297..39bc4c1d969a55088130cd00aa11e12f83b2dba2 100644
--- a/packages/backend/src/server/FileServerService.ts
+++ b/packages/backend/src/server/FileServerService.ts
@@ -137,38 +137,38 @@ export class FileServerService {
 
 		try {
 			if (file.state === 'remote') {
-				const convertFile = async () => {
-					if (file.fileRole === 'thumbnail') {
-						if (['image/jpeg', 'image/webp', 'image/avif', 'image/png', 'image/svg+xml'].includes(file.mime)) {
-							return this.imageProcessingService.convertToWebpStream(
-								file.path,
-								498,
-								280
-							);
-						} else if (file.mime.startsWith('video/')) {
-							return await this.videoProcessingService.generateVideoThumbnail(file.path);
-						}
+				let image: IImageStreamable | null = null;
+
+				if (file.fileRole === 'thumbnail') {
+					if (isMimeImage(file.mime, 'sharp-convertible-image')) {
+						reply.header('Cache-Control', 'max-age=31536000, immutable');
+
+						const url = new URL(`${this.config.mediaProxy}/static.webp`);
+						url.searchParams.set('url', file.url);
+						url.searchParams.set('static', '1');
+						return await reply.redirect(301, url.toString());
+					} else if (file.mime.startsWith('video/')) {
+						image = await this.videoProcessingService.generateVideoThumbnail(file.path);
 					}
+				}
+
+				if (file.fileRole === 'webpublic') {
+					if (['image/svg+xml'].includes(file.mime)) {
+						reply.header('Cache-Control', 'max-age=31536000, immutable');
 
-					if (file.fileRole === 'webpublic') {
-						if (['image/svg+xml'].includes(file.mime)) {
-							return this.imageProcessingService.convertToWebpStream(
-								file.path,
-								2048,
-								2048,
-								{ ...webpDefault, lossless: true }
-							)
-						}
+						const url = new URL(`${this.config.mediaProxy}/svg.webp`);
+						url.searchParams.set('url', file.url);
+						return await reply.redirect(301, url.toString());
 					}
+				}
 
-					return {
+				if (!image) {
+					image = {
 						data: fs.createReadStream(file.path),
 						ext: file.ext,
 						type: file.mime,
 					};
-				};
-
-				const image = await convertFile();
+				}
 
 				if ('pipe' in image.data && typeof image.data.pipe === 'function') {
 					// image.dataがstreamなら、stream終了後にcleanup
@@ -180,7 +180,6 @@ export class FileServerService {
 				}
 
 				reply.header('Content-Type', FILE_TYPE_BROWSERSAFE.includes(image.type) ? image.type : 'application/octet-stream');
-				reply.header('Cache-Control', 'max-age=31536000, immutable');
 				return image.data;
 			}
 
@@ -217,6 +216,23 @@ export class FileServerService {
 			return;
 		}
 
+		if (this.config.externalMediaProxyEnabled) {
+			// 外部のメディアプロキシが有効なら、そちらにリダイレクト
+
+			reply.header('Cache-Control', 'public, max-age=259200'); // 3 days
+
+			const url = new URL(`${this.config.mediaProxy}/${request.params.url || ''}`);
+
+			for (const [key, value] of Object.entries(request.query)) {
+				url.searchParams.append(key, value);
+			}
+
+			return await reply.redirect(
+				301,
+				url.toString(),
+			);
+		}
+
 		// Create temp file
 		const file = await this.getStreamAndTypeFromUrl(url);
 		if (file === '404') {
@@ -236,7 +252,7 @@ export class FileServerService {
 			const isAnimationConvertibleImage = isMimeImage(file.mime, 'sharp-animation-convertible-image');
 
 			let image: IImageStreamable | null = null;
-			if ('emoji' in request.query && isConvertibleImage) {
+			if (('emoji' in request.query || 'avatar' in request.query) && isConvertibleImage) {
 				if (!isAnimationConvertibleImage && !('static' in request.query)) {
 					image = {
 						data: fs.createReadStream(file.path),
@@ -246,7 +262,7 @@ export class FileServerService {
 				} else {
 					const data = sharp(file.path, { animated: !('static' in request.query) })
 							.resize({
-								height: 128,
+								height: 'emoji' in request.query ? 128 : 320,
 								withoutEnlargement: true,
 							})
 							.webp(webpDefault);
@@ -370,7 +386,7 @@ export class FileServerService {
 
 	@bindThis
 	private async getFileFromKey(key: string): Promise<
-		{ state: 'remote'; fileRole: 'thumbnail' | 'webpublic' | 'original'; file: DriveFile; mime: string; ext: string | null; path: string; cleanup: () => void; }
+		{ state: 'remote'; fileRole: 'thumbnail' | 'webpublic' | 'original'; file: DriveFile; url: string; mime: string; ext: string | null; path: string; cleanup: () => void; }
 		| { state: 'stored_internal'; fileRole: 'thumbnail' | 'webpublic' | 'original'; file: DriveFile; mime: string; ext: string | null; path: string; }
 		| '404'
 		| '204'
@@ -392,6 +408,7 @@ export class FileServerService {
 			const result = await this.downloadAndDetectTypeFromUrl(file.uri);
 			return {
 				...result,
+				url: file.uri,
 				fileRole: isThumbnail ? 'thumbnail' : isWebpublic ? 'webpublic' : 'original',
 				file,
 			}
diff --git a/packages/backend/src/server/ServerService.ts b/packages/backend/src/server/ServerService.ts
index beb3a34ecdd25e966e95956a6ea2397cb2432955..c7a2c99f949ba14a3e990fc2b9673e560f1ffd3a 100644
--- a/packages/backend/src/server/ServerService.ts
+++ b/packages/backend/src/server/ServerService.ts
@@ -106,7 +106,7 @@ export class ServerService {
 				}
 			}
 
-			const url = new URL('/proxy/emoji.webp', this.config.url);
+			const url = new URL(`${this.config.mediaProxy}/emoji.webp`);
 			// || emoji.originalUrl してるのは後方互換性のため（publicUrlはstringなので??はだめ）
 			url.searchParams.set('url', emoji.publicUrl || emoji.originalUrl);
 			url.searchParams.set('emoji', '1');
diff --git a/packages/backend/src/server/api/endpoints/meta.ts b/packages/backend/src/server/api/endpoints/meta.ts
index 3baf9453237e70708ee992dc4e819453fc6cb164..2fa7a09d49af741d141da521b4a0d2c2587d40ef 100644
--- a/packages/backend/src/server/api/endpoints/meta.ts
+++ b/packages/backend/src/server/api/endpoints/meta.ts
@@ -181,6 +181,10 @@ export const meta = {
 				type: 'string',
 				optional: false, nullable: true,
 			},
+			mediaProxy: {
+				type: 'string',
+				optional: false, nullable: false,
+			},
 			features: {
 				type: 'object',
 				optional: true, nullable: false,
@@ -307,6 +311,8 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 
 				policies: { ...DEFAULT_POLICIES, ...instance.policies },
 
+				mediaProxy: this.config.mediaProxy,
+
 				...(ps.detail ? {
 					pinnedPages: instance.pinnedPages,
 					pinnedClipId: instance.pinnedClipId,
diff --git a/packages/backend/src/server/web/UrlPreviewService.ts b/packages/backend/src/server/web/UrlPreviewService.ts
index 802b404ce65dd9fa5b4cb537fa04b0218555575e..1bf88fe4345810534b84a7dc318a4395a5a50a93 100644
--- a/packages/backend/src/server/web/UrlPreviewService.ts
+++ b/packages/backend/src/server/web/UrlPreviewService.ts
@@ -33,7 +33,7 @@ export class UrlPreviewService {
 	private wrap(url?: string): string | null {
 		return url != null
 			? url.match(/^https?:\/\//)
-				? `${this.config.url}/proxy/preview.webp?${query({
+				? `${this.config.mediaProxy}/preview.webp?${query({
 					url,
 					preview: '1',
 				})}`
diff --git a/packages/frontend/src/scripts/media-proxy.ts b/packages/frontend/src/scripts/media-proxy.ts
index bea164e7c8585f78a61e474aae5bd2c966db704b..274e96e0a105d7bdd536e129b858e23beef8701f 100644
--- a/packages/frontend/src/scripts/media-proxy.ts
+++ b/packages/frontend/src/scripts/media-proxy.ts
@@ -1,8 +1,9 @@
 import { query, appendQuery } from '@/scripts/url';
 import { url } from '@/config';
+import { instance } from '@/instance';
 
 export function getProxiedImageUrl(imageUrl: string, type?: 'preview'): string {
-	if (imageUrl.startsWith(`${url}/proxy/`) || imageUrl.startsWith('/proxy/')) {
+	if (imageUrl.startsWith(instance.mediaProxy + '/') || imageUrl.startsWith('/proxy/')) {
 		// もう既にproxyっぽそうだったらsearchParams付けるだけ
 		return appendQuery(imageUrl, query({
 			fallback: '1',
@@ -10,7 +11,7 @@ export function getProxiedImageUrl(imageUrl: string, type?: 'preview'): string {
 		}));
 	}
 
-	return `${url}/proxy/image.webp?${query({
+	return `${instance.mediaProxy}/image.webp?${query({
 		url: imageUrl,
 		fallback: '1',
 		...(type ? { [type]: '1' } : {}),
@@ -25,22 +26,19 @@ export function getProxiedImageUrlNullable(imageUrl: string | null | undefined,
 export function getStaticImageUrl(baseUrl: string): string {
 	const u = baseUrl.startsWith('http') ? new URL(baseUrl) : new URL(baseUrl, url);
 
-	if (u.href.startsWith(`${url}/proxy/`)) {
-		// もう既にproxyっぽそうだったらsearchParams付けるだけ
+	if (u.href.startsWith(`${url}/emoji/`)) {
+		// もう既にemojiっぽそうだったらsearchParams付けるだけ
 		u.searchParams.set('static', '1');
 		return u.href;
 	}
 
-	if (u.href.startsWith(`${url}/emoji/`)) {
-		// もう既にemojiっぽそうだったらsearchParams付けるだけ
+	if (u.href.startsWith(instance.mediaProxy + '/')) {
+		// もう既にproxyっぽそうだったらsearchParams付けるだけ
 		u.searchParams.set('static', '1');
 		return u.href;
 	}
 
-	// 拡張子がないとキャッシュしてくれないCDNがあるのでダミーの名前を指定する
-	const dummy = `${encodeURIComponent(`${u.host}${u.pathname}`)}.webp`;
-
-	return `${url}/proxy/${dummy}?${query({
+	return `${instance.mediaProxy}/static.webp?${query({
 		url: u.href,
 		static: '1',
 	})}`;