diff --git a/.github/workflows/test.benchmark.yml b/.github/workflows/test.benchmark.yml
deleted file mode 100644
index 45b1fcf..0000000
--- a/.github/workflows/test.benchmark.yml
+++ /dev/null
@@ -1,26 +0,0 @@
-name: test:benchmark
-
-on:
-    workflow_dispatch:
-
-jobs:
-    benchmark:
-        runs-on: ubuntu-latest
-
-        steps:
-            - uses: actions/checkout@v4
-
-            - name: Setup Node.js
-              uses: actions/setup-node@v3
-              with:
-                  node-version: '20'
-                  cache: npm
-                  cache-dependency-path: package-lock.json
-
-            - name: start server
-              run: docker compose up -d
-
-            - name: run test
-              run: |
-                  npm ci
-                  npm run test:benchmark
diff --git a/package.json b/package.json
index aa67f8f..6c943db 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
   "type": "module",
   "name": "chiitiler",
-  "version": "1.12.7",
+  "version": "1.13.0",
   "description": "Tiny map rendering server for MapLibre Style Spec",
   "main": "./dist/index.js",
   "types": "./dist/index.d.ts",
diff --git a/src/index.test.ts b/src/index.test.ts
new file mode 100644
index 0000000..e8a1010
--- /dev/null
+++ b/src/index.test.ts
@@ -0,0 +1,25 @@
+import { describe, it, expect } from 'vitest';
+
+import {
+    getRenderedBboxBuffer,
+    getRenderedBboxStream,
+    getRenderedTileBuffer,
+    getRenderedTileStream,
+    ChiitilerCache,
+} from './index.js';
+
+describe('library mode', () => {
+    // testing actual behavior of rendering methods is difficult...
+    it('members are exported', async () => {
+        expect(getRenderedBboxBuffer).toBeDefined();
+        expect(getRenderedBboxStream).toBeDefined();
+        expect(getRenderedTileBuffer).toBeDefined();
+        expect(getRenderedTileStream).toBeDefined();
+
+        // actual behaviors are tested in cache module
+        expect(ChiitilerCache.fileCache).toBeDefined();
+        expect(ChiitilerCache.memoryCache).toBeDefined();
+        expect(ChiitilerCache.noneCache).toBeDefined();
+        expect(ChiitilerCache.s3Cache).toBeDefined();
+    });
+});
diff --git a/src/server/index.test.ts b/src/server/index.test.ts
index b51f1bd..330f8f2 100644
--- a/src/server/index.test.ts
+++ b/src/server/index.test.ts
@@ -11,6 +11,7 @@ describe('initServer', () => {
             port: 8989,
             cache: cache.noneCache(),
             debug: false,
+            stream: false,
         });
         const res = await app.request('/health');
         expect(res.status).toBe(200);
@@ -28,6 +29,7 @@ describe('initServer', () => {
             port: 8989,
             cache: cache.noneCache(),
             debug: true,
+            stream: false,
         });
         const res = await app.request('/health');
         expect(res.status).toBe(200);
@@ -45,6 +47,7 @@ describe('initServer', () => {
             port: 8989,
             cache: cache.noneCache(),
             debug: false,
+            stream: false,
         });
 
         const res = await app.request('/tiles/0/0/0.png');
@@ -71,6 +74,7 @@ describe('initServer', () => {
             port: 8989,
             cache: cache.noneCache(),
             debug: false,
+            stream: false,
         });
 
         const res = await app.request('/clip.png?bbox=0,1,2,3');
diff --git a/src/server/index.ts b/src/server/index.ts
index a2455d5..dfaa249 100644
--- a/src/server/index.ts
+++ b/src/server/index.ts
@@ -113,6 +113,8 @@ function initServer(options: InitServerOptions): InitializedServer {
             const quality = Number(c.req.query('quality') ?? 100);
             const margin = Number(c.req.query('margin') ?? 0);
 
+            c.header('Content-Type', `image/${ext}`);
+
             try {
                 const sharp = await getRenderedTile({
                     stylejson: style,
@@ -162,6 +164,8 @@ function initServer(options: InitServerOptions): InitializedServer {
             const quality = Number(c.req.query('quality') ?? 100);
             const size = Number(c.req.query('size') ?? 1024);
 
+            c.header('Content-Type', `image/${ext}`);
+
             try {
                 const sharp = await getRenderedBbox({
                     stylejson: url,
@@ -209,6 +213,8 @@ function initServer(options: InitServerOptions): InitializedServer {
             const quality = Number(c.req.query('quality') ?? 100);
             const size = Number(c.req.query('size') ?? 1024);
 
+            c.header('Content-Type', `image/${ext}`);
+
             try {
                 const sharp = await getRenderedBbox({
                     stylejson: style,