diff --git a/lib/data-provider.js b/lib/data-provider.js
index f24bbe3..fa66ff5 100644
--- a/lib/data-provider.js
+++ b/lib/data-provider.js
@@ -1,9 +1,6 @@
 'use strict';
 
 const url = require('url');
-const defaultHeaders = {
-    Accept: 'text/html, application/xhtml+xml, application/xml',
-};
 
 module.exports = function DataProvider(config) {
     const pendingReqests = new Map();
@@ -12,6 +9,11 @@ module.exports = function DataProvider(config) {
 
     const baseUrl = config.baseUrl || '';
     const httpClient = config.httpClient || globalThis.fetch;
+    const userAgent = config.userAgent || 'node-esi';
+    const defaultHeaders = {
+        Accept: 'text/html, application/xhtml+xml, application/xml',
+        'user-agent': userAgent,
+    };
 
     function extendRequestOptions(src, baseOptions) {
         return [
diff --git a/test/data-provider-test.js b/test/data-provider-test.js
index 0ecb179..b99dab5 100644
--- a/test/data-provider-test.js
+++ b/test/data-provider-test.js
@@ -92,10 +92,39 @@ describe('Data Provider', () => {
             .catch(done);
     });
 
+    it('allows to configure custom user agent', (done) => {
+        // given
+        let calledUserAgent;
+        const userAgent = 'my-custom-agent';
+        const server = http.createServer((req, res) => {
+            calledUserAgent = req.headers['user-agent'];
+            res.writeHead(200, { 'Content-Type': 'text/html' });
+            res.end('stuff');
+        });
+        server.listen();
+
+        const port = server.address().port;
+        const dataProvider = new DataProvider({
+            baseUrl: `http://localhost:${port}`,
+            userAgent,
+        });
+
+        // when
+        dataProvider
+            .get('/')
+
+            // then
+            .then((result) => {
+                assert.equal(result, 'stuff');
+                assert.equal(calledUserAgent, userAgent);
+                done();
+            })
+            .catch(done);
+    });
+
     it('should work with a custom http client that is fetch api compatible', (done) => {
         // given
         const baseUrl = 'http://example.com';
-        const userAgent = 'my-custom-agent';
         let calledUrl;
         let calledOptions;
 
@@ -113,7 +142,10 @@ describe('Data Provider', () => {
 
         // when
         dataProvider
-            .get('/path', { headers: { 'user-agent': userAgent } })
+            .get('/path', {
+                headers: { custom: 'custom-header-value' },
+                optionX: 'optionX',
+            })
 
             // then
             .then((result) => {
@@ -122,8 +154,10 @@ describe('Data Provider', () => {
                 assert.deepEqual(calledOptions, {
                     headers: {
                         Accept: 'text/html, application/xhtml+xml, application/xml',
-                        'user-agent': userAgent,
+                        'user-agent': 'node-esi',
+                        custom: 'custom-header-value',
                     },
+                    optionX: 'optionX',
                 });
                 done();
             })
diff --git a/test/e2e-test.js b/test/e2e-test.js
index 6867c1e..20ebe01 100644
--- a/test/e2e-test.js
+++ b/test/e2e-test.js
@@ -29,10 +29,7 @@ describe('ESI processor', () => {
             res.end('<div>test</div>');
         });
 
-        const html =
-            '<section></section>';
+        const html = `<section></section>`;
 
         // when
         const processed = ESI().process(html);
@@ -58,12 +55,7 @@ describe('ESI processor', () => {
             }
         });
 
-        const html =
-            '<section></section>';
+        const html = `<section><!-- bad ESI request: bad ESI request --></section>`;
 
         // when
         const processed = ESI().process(html);
@@ -92,12 +84,7 @@ describe('ESI processor', () => {
             }
         });
 
-        const html =
-            '<section></section>';
+        const html = `<section><!-- bad ESI request: bad ESI request --></section>`;
 
         // when
         const processed = ESI().process(html);
@@ -124,10 +111,7 @@ describe('ESI processor', () => {
             res.end('<div>test</div>');
         });
 
-        const html =
-            "<section></section>";
+        const html = `<section></section>`;
 
         // when
         const processed = ESI().process(html);
@@ -153,12 +137,7 @@ describe('ESI processor', () => {
             }
         });
 
-        const html =
-            '<section></section>";
+        const html = `<section></section>`;
 
         // when
         const processed = ESI().process(html);
@@ -176,13 +155,10 @@ describe('ESI processor', () => {
         // given
         server.addListener('request', (req, res) => {
             res.writeHead(200, { 'Content-Type': 'text/html' });
-            res.end('<div>' + req.url + '</div>');
+            res.end(`<div>${req.url}</div>`);
         });
 
-        const html =
-            "<section></section>";
+        const html = `<section></section>`;
 
         // when
         const processed = ESI().process(html);
@@ -206,10 +182,7 @@ describe('ESI processor', () => {
             res.end('<div>test</div>');
         });
 
-        const html =
-            '<section></section>';
+        const html = `<section></section>`;
 
         // when
         const processed = ESI().process(html);
@@ -235,12 +208,7 @@ describe('ESI processor', () => {
             }
         });
 
-        const html =
-            '<section></section>';
+        const html = `<section></section>`;
 
         // when
         const processed = ESI().process(html);
@@ -261,10 +229,7 @@ describe('ESI processor', () => {
             res.end('<div>test</div>');
         });
 
-        const html =
-            '<section></section>';
+        const html = `<section></section>`;
 
         // when
         const processed = ESI().process(html);
@@ -279,10 +244,7 @@ describe('ESI processor', () => {
     });
 
     it('should fetch nothing on typo', (done) => {
-        const html =
-            '<section></section>';
+        const html = `<section></section>`;
 
         // when
         const processed = ESI().process(html);
@@ -297,10 +259,7 @@ describe('ESI processor', () => {
     });
 
     it('should not process not properly closed tags', (done) => {
-        const html =
-            '<section></section>';
+        const html = `<section></section>`;
 
         // when
         const processed = ESI().process(html);
@@ -321,10 +280,7 @@ describe('ESI processor', () => {
             res.end('<div>test</div>');
         });
 
-        const html =
-            '<section><img src="some-image" /></section>';
+        const html = `<section><img src="some-image" /></section>`;
 
         // when
         const processed = ESI().process(html);
@@ -536,7 +492,7 @@ describe('ESI processor', () => {
                     error.message,
                     'HTTP error 500: Internal Server Error'
                 );
-                assert.equal(src, 'http://localhost:' + port + '/error');
+                assert.equal(src, `http://localhost:${port}/error`);
                 return '<div>something went wrong</div>';
             },
         }).process(html);
@@ -586,66 +542,24 @@ describe('ESI processor', () => {
             .catch(done);
     });
 
-    it('should allow to disable cache', (done) => {
-        // given
-        let connectionCount = 0;
-        server.addListener('request', (req, res) => {
-            res.writeHead(200, { 'Content-Type': 'text/html' });
-            if (connectionCount === 0) {
-                res.end('hello');
-            } else {
-                res.end('world');
-            }
-            connectionCount++;
-        });
-
-        const html = '<!-- bad ESI request: bad ESI request -->';
-
-        // when
-        const esi = ESI({
-            baseUrl: 'http://localhost:' + port,
-            cache: false,
-        });
-
-        const processed = esi.process(html);
-
-        // then
-        processed
-            .then((response) => {
-                return esi.process(html);
-            })
-            .then((response) => {
-                assert.equal(response, 'world');
-                done();
-            })
-            .catch(done);
-    });
-
     it('should fetch components recursively', (done) => {
         // given
         server.addListener('request', (req, res) => {
             res.writeHead(200, { 'Content-Type': 'text/html' });
             if (req.url === '/first') {
                 res.end(
-                    ''
+                    `<!-- bad ESI request: bad ESI request -->`
                 );
             } else if (req.url === '/second') {
                 res.end(
-                    ''
+                    `<!-- bad ESI request: bad ESI request -->`
                 );
             } else {
                 res.end('<div>test</div>');
             }
         });
 
-        const html =
-            '<section></section>';
+        const html = `<section><!-- bad ESI request: bad ESI request --></section>`;
 
         // when
         const processed = ESI().process(html);
@@ -664,16 +578,11 @@ describe('ESI processor', () => {
         server.addListener('request', (req, res) => {
             res.writeHead(200, { 'Content-Type': 'text/html' });
             res.end(
-                ''
+                ``
             );
         });
 
-        const html =
-            '<section></section>';
+        const html = `<section></section>`;
 
         // when
         const processed = ESI({
@@ -701,10 +610,7 @@ describe('ESI processor', () => {
             }
         });
 
-        const html =
-            '<section></section>';
+        const html = `<section></section>`;
 
         // when
         const processed = ESI().process(html, {
@@ -722,6 +628,49 @@ describe('ESI processor', () => {
             .catch(done);
     });
 
+    it('should pass a default user-agent header to the server', (done) => {
+        // given
+        server.addListener('request', (req, res) => {
+            res.writeHead(200, { 'Content-Type': 'text/html' });
+            res.end(req.headers['user-agent']);
+        });
+
+        const html = `<section></section>`;
+
+        // when
+        const processed = ESI().process(html);
+
+        // then
+        processed
+            .then((response) => {
+                assert.equal(response, '<section>node-esi</section>');
+                done();
+            })
+            .catch(done);
+    });
+
+    it('should pass a custom user-agent header to the server', (done) => {
+        // given
+        const userAgent = 'my-custom-agent';
+        server.addListener('request', (req, res) => {
+            res.writeHead(200, { 'Content-Type': 'text/html' });
+            res.end(req.headers['user-agent']);
+        });
+
+        const html = `<section></section>`;
+
+        // when
+        const processed = ESI({ userAgent }).process(html);
+
+        // then
+        processed
+            .then((response) => {
+                assert.equal(response, `<section>${userAgent}</section>`);
+                done();
+            })
+            .catch(done);
+    });
+
     it('should throw appropriate error if the host was blocked', (done) => {
         // given
         server.addListener('request', (req, res) => {
@@ -729,10 +678,7 @@ describe('ESI processor', () => {
             res.end('<div>test</div>');
         });
 
-        const html =
-            '<section></section>';
+        const html = `<section></section>`;
 
         const esi = ESI({
             allowedHosts: ['http://not-localhost'],
@@ -758,10 +704,7 @@ describe('ESI processor', () => {
             res.end('<div>test</div>');
         });
 
-        const html =
-            '<section></section>';
+        const html = `<section></section>`;
 
         const errors = [];
         const esi = ESI({
@@ -789,10 +732,7 @@ describe('ESI processor', () => {
             res.end('<div>test</div>');
         });
 
-        const html =
-            '<section></section>';
+        const html = `<section></section>`;
 
         const errors = [];
         const esi = ESI({
@@ -990,7 +930,7 @@ describe('ESI processor', () => {
 
         // when
         const processed = ESI({
-            baseUrl: 'http://localhost:' + port,
+            baseUrl: `http://localhost:${port}`,
         }).process(html);
 
         // then