diff --git a/sdk/build.gradle b/sdk/build.gradle
index f78c5ddc..92e7a319 100644
--- a/sdk/build.gradle
+++ b/sdk/build.gradle
@@ -7,6 +7,11 @@ plugins {
     id "com.github.spotbugs" version "5.2.3"
     id "org.owasp.dependencycheck" version "7.1.1"
     id "org.sonarqube" version "3.4.0.2513"
+    id "de.undercouch.download" version "5.5.0"
+}
+
+ext {
+    hcaptchaLoaderVersion = "1.2.4"
 }
 
 android {
@@ -18,7 +23,7 @@ android {
     }
 
     defaultConfig {
-        minSdkVersion 16
+        minSdkVersion 16 // Android 4.1
         targetSdkVersion 34
 
         // See https://developer.android.com/studio/publish/versioning
@@ -31,6 +36,7 @@ android {
         versionName "4.0.0"
 
         buildConfigField 'String', 'VERSION_NAME', "\"${defaultConfig.versionName}_${defaultConfig.versionCode}\""
+        buildConfigField 'String', 'LOADER_VERSION', "\"${hcaptchaLoaderVersion}\""
 
         consumerProguardFiles "consumer-rules.pro"
         proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
@@ -111,7 +117,31 @@ project.afterEvaluate {
     }
 }
 
-long MAX_AAR_SIZE_KB = 200
+long MAX_AAR_SIZE_KB = 250
+
+String sha256Integrity(String filename) {
+    def file = new File("${buildDir}/generated/assets/hcaptcha/${filename}")
+    def sha256Hash = file.withInputStream { stream ->
+        org.apache.commons.codec.digest.DigestUtils.sha256(stream)
+    }
+    def base64Hash = org.apache.commons.codec.binary.Base64.encodeBase64String(sha256Hash)
+
+    return "sha256-${base64Hash}"
+}
+
+tasks.register('downloadPolyfillsJs', Download) {
+    src "https://www.unpkg.com/@hcaptcha/loader@${hcaptchaLoaderVersion}/dist/polyfills.js"
+    dest layout.buildDirectory.file("generated/assets/hcaptcha/polyfills.js")
+    onlyIfModified true
+}
+
+tasks.register('downloadHCaptchaLoaderJs', Download) {
+    src "https://www.unpkg.com/@hcaptcha/loader@${hcaptchaLoaderVersion}/dist/index.es5.js"
+    dest layout.buildDirectory.file("generated/assets/hcaptcha/loader.js")
+    onlyIfModified true
+}.get().dependsOn('downloadPolyfillsJs')
+
+android.sourceSets.main.assets.srcDirs += [layout.buildDirectory.file("generated/assets")]
 
 android.libraryVariants.all { variant ->
     def variantName = variant.name.capitalize()
@@ -136,7 +166,7 @@ android.libraryVariants.all { variant ->
             var aarFile = variant.packageLibraryProvider.get().archiveFile.get().getAsFile()
             long aarSizeKb = aarFile.length() / 1024
             if (aarSizeKb > MAX_AAR_SIZE_KB) {
-                throw new GradleException("${aarPath} size exceeded! ${aarSizeKb}Kbyte > ${MAX_AAR_SIZE_KB}Kbyte")
+                throw new GradleException("${aarFile} size exceeded! ${aarSizeKb}Kbyte > ${MAX_AAR_SIZE_KB}Kbyte")
             }
         }
     })
@@ -150,9 +180,14 @@ android.libraryVariants.all { variant ->
         doFirst {
             def outputJavaClass = file("$outputDir/HCaptchaHtml.java")
             def template = file("$projectDir/src/main/html/HCaptchaHtml.java.tml").text
+            def polyfillsIntegrity = sha256Integrity('polyfills.js')
+            def loaderIntegrity = sha256Integrity('loader.js')
             def html = file("$projectDir/src/main/html/hcaptcha.html")
                     .readLines()
                     .stream()
+                    .map({l -> "${l.replaceAll('@LOADER_VERSION@', hcaptchaLoaderVersion)}"})
+                    .map({l -> "${l.replaceAll('@POLYFILLS_INTEGRITY@', polyfillsIntegrity)}"})
+                    .map({l -> "${l.replaceAll('@LOADER_INTEGRITY@', loaderIntegrity)}"})
                     .map({l -> "\"${l.replaceAll('"', '\\\\"')}\\n\""})
                     .collect(java.util.stream.Collectors.joining("\n${' ' * 16}+ "))
 
@@ -167,8 +202,15 @@ android.libraryVariants.all { variant ->
         }
     }
 
-    // preBuild.dependsOn generateTask
     variant.registerJavaGeneratingTask(generateTask, outputDir)
+    generateTask.dependsOn(downloadHCaptchaLoaderJs)
+
+    tasks.named("package${variant.name.capitalize()}Assets")
+            .get()
+            .dependsOn(downloadHCaptchaLoaderJs)
+    tasks.named("merge${variant.name.capitalize()}Assets")
+            .get()
+            .dependsOn(downloadHCaptchaLoaderJs)
 }
 
 apply from: "$rootProject.projectDir/gradle/shared/code-quality.gradle"
\ No newline at end of file
diff --git a/sdk/src/main/html/hcaptcha.html b/sdk/src/main/html/hcaptcha.html
index 770989c4..051908e4 100644
--- a/sdk/src/main/html/hcaptcha.html
+++ b/sdk/src/main/html/hcaptcha.html
@@ -36,7 +36,9 @@
         window.sysDebug = JSON.parse(window.JSDI.getSysDebug());
     }
 </script>
-<script type="text/javascript">
+<script type="text/javascript" integrity="@POLYFILLS_INTEGRITY@" crossorigin="anonymous" src="https://unpkg.com/@hcaptcha/loader@@LOADER_VERSION@/dist/polyfills.js"></script>
+<script type="text/javascript" integrity="@LOADER_INTEGRITY@" crossorigin="anonymous" src="https://unpkg.com/@hcaptcha/loader@@LOADER_VERSION@/dist/index.es5.js"></script>
+<script>
     // Android will inject this bridge object as `JSInterface`
     // Browser is missing it, so we mock it
     var BridgeObject = window.JSInterface || {
@@ -70,20 +72,40 @@
         }
     };
     var bridgeConfig = JSON.parse(BridgeObject.getConfig());
-    var hCaptchaID = null;
     /**
      * Called programmatically from HCaptchaWebViewHelper.
      */
     function resetAndExecute() {
         hcaptcha.reset();
-        hcaptcha.execute(hCaptchaID);
+        execute();
     }
+    window.resetAndExecute = resetAndExecute;
     function reset() {
         hcaptcha.reset();
     }
-    function getTheme(bridgeConfig) {
-        var theme = bridgeConfig.theme;
-        var customTheme = bridgeConfig.customTheme;
+
+    function errorCallback(error) {
+        switch(error) {
+            case "rate-limited":
+                return BridgeObject.onError(31);
+            case "network-error":
+                return BridgeObject.onError(7);
+            case "invalid-data":
+                return BridgeObject.onError(8);
+            case "challenge-error":
+                return BridgeObject.onError(9);
+            case "internal-error":
+                return BridgeObject.onError(10);
+            default:
+                // Error not handled? Log it for debugging purposes
+                console.error(error);
+                return BridgeObject.onError(29);
+        }
+    }
+
+    function getTheme(config) {
+        var theme = config.theme;
+        var customTheme = config.customTheme;
         if (customTheme) {
             try {
                 return JSON.parse(customTheme);
@@ -94,112 +116,94 @@
         }
         return theme;
     }
-    function getRenderConfig() {
+    function getRenderConfig(config) {
         return {
-            sitekey: bridgeConfig.siteKey,
-            size: bridgeConfig.size,
-            orientation: bridgeConfig.orientation,
-            theme: getTheme(bridgeConfig),
+            sitekey: config.siteKey,
+            size: config.size,
+            orientation: config.orientation,
+            theme: getTheme(config),
+            host: config.host || config.siteKey + '.android-sdk.hcaptcha.com',
             callback: function callback(token) {
+                console.log("callback");
                 return BridgeObject.onPass(token);
             },
             'chalexpired-callback': function chalexpiredCallback() {
+                console.log("chalexpired-callback");
                 return BridgeObject.onError(15);
             },
             'close-callback': function closeCallback() {
+                console.log("close-callback");
                 return BridgeObject.onError(30);
             },
-            'error-callback': function errorCallback(error) {
-                switch(error) {
-                    case "rate-limited":
-                        return BridgeObject.onError(31);
-                    case "network-error":
-                        return BridgeObject.onError(7);
-                    case "invalid-data":
-                        return BridgeObject.onError(8);
-                    case "challenge-error":
-                        return BridgeObject.onError(9);
-                    case "internal-error":
-                        return BridgeObject.onError(10);
-                    default:
-                        // Error not handled? Log it for debugging purposes
-                        console.error(error);
-                        return BridgeObject.onError(29);
-                }
-            },
             'open-callback': function openCallback() {
                 return BridgeObject.onOpen();
-            }
+            },
+            'error-callback': errorCallback
         };
     }
-    function onHcaptchaLoaded() {
-        try {
-            var renderConfig = getRenderConfig();
-            hCaptchaID = hcaptcha.render('hcaptcha-container', renderConfig);
-            BridgeObject.onLoaded();
-            var rqdata = bridgeConfig.rqdata;
-            if (rqdata) {
-                hcaptcha.setData(hCaptchaID, { rqdata: rqdata });
-            }
-            if (renderConfig.size === 'invisible' && !bridgeConfig.hideDialog) {
-                // We want to auto execute in case of `invisible` checkbox.
-                // But not in case of `hideDialog` since verification process
-                // might be desired to happen at a later time.
-                hcaptcha.execute(hCaptchaID);
-            }
-        } catch (e) {
-            console.error(e);
-            BridgeObject.onError(29);
-        }
-    }
-    function addQueryParamIfDefined(url, queryName, queryValue) {
-        if (queryValue !== undefined && queryValue !== null) {
-            var link = url.indexOf('?') !== -1 ? '&' : '?';
-            return url + link + queryName + '=' + encodeURIComponent(queryValue);
-        }
-        return url;
-    }
-    function loadApi() {
-        var siteKey = bridgeConfig.siteKey;
-        var locale = bridgeConfig.locale;
-        var sentry = bridgeConfig.sentry;
-        var jsSrc = bridgeConfig.jsSrc;
-        var endpoint = bridgeConfig.endpoint;
-        var assethost = bridgeConfig.assethost;
-        var imghost = bridgeConfig.imghost;
-        var reportapi = bridgeConfig.reportapi;
-        var host = bridgeConfig.host || siteKey + '.android-sdk.hcaptcha.com';
-        var scriptSrc = jsSrc + '?render=explicit&onload=' + onHcaptchaLoaded.name;
-        scriptSrc = addQueryParamIfDefined(scriptSrc, 'recaptchacompat', 'off');
-        scriptSrc = addQueryParamIfDefined(scriptSrc, 'hl', locale);
-        scriptSrc = addQueryParamIfDefined(scriptSrc, 'host', host);
-        scriptSrc = addQueryParamIfDefined(scriptSrc, 'sentry', sentry);
-        scriptSrc = addQueryParamIfDefined(scriptSrc, 'endpoint', endpoint);
-        scriptSrc = addQueryParamIfDefined(scriptSrc, 'assethost', assethost);
-        scriptSrc = addQueryParamIfDefined(scriptSrc, 'imghost', imghost);
-        scriptSrc = addQueryParamIfDefined(scriptSrc, 'reportapi', reportapi);
-        if (bridgeConfig.customTheme) {
-            scriptSrc = addQueryParamIfDefined(scriptSrc, 'custom', 'true');
-        }
-        var script = document.createElement('script');
-        script.async = true;
-        script.src = scriptSrc;
-        script.onerror = function () {
-            // network issue
-            BridgeObject.onError(7);
+    function getScriptParams(config) {
+        return {
+            scriptLocation: document.head,
+            apihost: config.jsSrc,
+            loadAsync: true,
+            async: true,
         };
-        document.head.appendChild(script);
+    }
+    function getLoaderParams(config) {
+        var result = getScriptParams(config);
+
+        result.render = 'explicit';
+        result.sentry = config.sentry;
+        result.custom = !!config.customTheme;
+        result.assethost = config.assethost;
+        result.imghost = config.imghost;
+        result.reportapi = config.reportapi;
+        result.endpoint = config.endpoint;
+        result.host = config.host || config.siteKey + '.android-sdk.hcaptcha.com';
+        result.recaptchacompat = 'off';
+        result.hl = config.locale;
+        result.cleanup = true;
+
+        return result;
     }
     var container = document.getElementById("hcaptcha-container");
     container.addEventListener("click", function () {
-        if (window.hcaptcha) {
+        if (hcaptcha) {
             // Allows dismissal of checkbox view
-            window.hcaptcha.close();
+            hcaptcha.close();
         } else {
             BridgeObject.onError(30);
         }
     });
-    loadApi();
+    function execute() {
+        hcaptcha.execute(getScriptParams(bridgeConfig)).then(function(result) {
+            var response = result.response;
+            BridgeObject.onPass(response);
+        }).catch(function(error) {
+            errorCallback(error);
+        });
+    }
+    function loadApi(config) {
+        hCaptchaLoader(getLoaderParams(config)).then(function(hcaptcha) {
+            var renderConfig = getRenderConfig(config);
+            hcaptcha.render("hcaptcha-container", renderConfig);
+            BridgeObject.onLoaded();
+            var rqdata = config.rqdata;
+            if (rqdata) {
+                hcaptcha.setData({ rqdata: rqdata });
+            }
+            if (renderConfig.size === 'invisible' && !config.hideDialog) {
+                // We want to auto execute in case of `invisible` checkbox.
+                // But not in case of `hideDialog` since verification process
+                // might be desired to happen at a later time.
+                execute();
+            }
+        }).catch(function(error) {
+            console.error("loadApi error", error);
+            BridgeObject.onError(29);
+        });
+    }
+    loadApi(bridgeConfig);
 </script>
 </body>
 </html>
diff --git a/sdk/src/main/java/com/hcaptcha/sdk/HCaptchaDialogFragment.java b/sdk/src/main/java/com/hcaptcha/sdk/HCaptchaDialogFragment.java
index c964ccf7..a59e0331 100644
--- a/sdk/src/main/java/com/hcaptcha/sdk/HCaptchaDialogFragment.java
+++ b/sdk/src/main/java/com/hcaptcha/sdk/HCaptchaDialogFragment.java
@@ -194,6 +194,7 @@ public void onAnimationEnd(Animator animation) {
 
     @Override
     public void onLoaded() {
+        HCaptchaLog.d("DialogFragment.onLoaded");
         assert webViewHelper != null;
 
         if (webViewHelper.getConfig().getSize() != HCaptchaSize.INVISIBLE) {
diff --git a/sdk/src/main/java/com/hcaptcha/sdk/HCaptchaHeadlessWebView.java b/sdk/src/main/java/com/hcaptcha/sdk/HCaptchaHeadlessWebView.java
index 60cd0a60..91f445f3 100644
--- a/sdk/src/main/java/com/hcaptcha/sdk/HCaptchaHeadlessWebView.java
+++ b/sdk/src/main/java/com/hcaptcha/sdk/HCaptchaHeadlessWebView.java
@@ -70,6 +70,7 @@ public void onSuccess(final String token) {
 
     @Override
     public void onLoaded() {
+        HCaptchaLog.d("HeadlessWebView.onLoaded");
         webViewLoaded = true;
         if (shouldResetOnLoad) {
             shouldResetOnLoad = false;
diff --git a/sdk/src/main/java/com/hcaptcha/sdk/HCaptchaWebViewHelper.java b/sdk/src/main/java/com/hcaptcha/sdk/HCaptchaWebViewHelper.java
index e86b58c3..5cd5a387 100644
--- a/sdk/src/main/java/com/hcaptcha/sdk/HCaptchaWebViewHelper.java
+++ b/sdk/src/main/java/com/hcaptcha/sdk/HCaptchaWebViewHelper.java
@@ -22,6 +22,12 @@
 import lombok.Getter;
 import lombok.NonNull;
 
+import java.io.IOException;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Objects;
+
 final class HCaptchaWebViewHelper {
     @NonNull
     private final Context context;
@@ -120,12 +126,17 @@ public boolean shouldRetry(HCaptchaException exception) {
 
     @RequiresApi(Build.VERSION_CODES.LOLLIPOP)
     private class HCaptchaWebClient extends WebViewClient {
+        private final Map<Uri, String> assetsCache = new HashMap<>();
 
         @NonNull
         private final Handler handler;
 
         HCaptchaWebClient(@NonNull Handler handler) {
             this.handler = handler;
+
+            final String baseUrl = "https://unpkg.com/@hcaptcha/loader@" + BuildConfig.LOADER_VERSION + "/dist";
+            assetsCache.put(Uri.parse(baseUrl + "/index.es5.js"), "hcaptcha/loader.js");
+            assetsCache.put(Uri.parse(baseUrl + "/polyfills.js"), "hcaptcha/polyfills.js");
         }
 
         private String stripUrl(String url) {
@@ -135,7 +146,23 @@ private String stripUrl(String url) {
         @Override
         public WebResourceResponse shouldInterceptRequest (final WebView view, final WebResourceRequest request) {
             final Uri requestUri = request.getUrl();
-            if (requestUri != null && requestUri.getScheme() != null && requestUri.getScheme().equals("http")) {
+            final String assetPath = assetsCache.get(requestUri);
+            if (assetPath != null) {
+                try {
+                    HCaptchaLog.d("[webview] shouldInterceptRequest return local asset for " + requestUri);
+                    return new WebResourceResponse(
+                            "application/javascript",
+                            "UTF-8",
+                            200,
+                            "OK",
+                            Collections.singletonMap("Access-Control-Allow-Origin",
+                                    Objects.toString(config.getHost(), "null")),
+                            view.getContext().getAssets().open(assetPath)
+                    );
+                } catch (IOException e) {
+                    HCaptchaLog.w("[webview] shouldInterceptRequest wasn't able to load " + assetPath + " from assets");
+                }
+            } else if (requestUri != null && requestUri.getScheme() != null && requestUri.getScheme().equals("http")) {
                 handler.post(() -> {
                     webView.removeJavascriptInterface(HCaptchaJSInterface.JS_INTERFACE_TAG);
                     webView.removeJavascriptInterface(HCaptchaDebugInfo.JS_INTERFACE_TAG);
diff --git a/test/src/androidTest/java/com/hcaptcha/sdk/HCaptchaWebViewHelperTest.java b/test/src/androidTest/java/com/hcaptcha/sdk/HCaptchaWebViewHelperTest.java
index 4501c9e3..259ff4bc 100644
--- a/test/src/androidTest/java/com/hcaptcha/sdk/HCaptchaWebViewHelperTest.java
+++ b/test/src/androidTest/java/com/hcaptcha/sdk/HCaptchaWebViewHelperTest.java
@@ -2,15 +2,20 @@
 
 import static com.hcaptcha.sdk.AssertUtil.failAsNonReachable;
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertTrue;
 import static org.mockito.Mockito.mock;
 
+import android.content.Context;
+import android.content.res.AssetManager;
 import android.app.Activity;
 import android.os.Handler;
 import android.os.Looper;
 
 import androidx.test.core.app.ActivityScenario;
+import androidx.test.core.app.ApplicationProvider;
 import androidx.test.ext.junit.rules.ActivityScenarioRule;
+import androidx.test.platform.app.InstrumentationRegistry;
 
 import com.hcaptcha.sdk.test.TestActivity;
 
@@ -18,6 +23,8 @@
 import org.junit.Rule;
 import org.junit.Test;
 
+import java.io.IOException;
+import java.io.InputStream;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
 
@@ -88,4 +95,22 @@ public void onFailure(HCaptchaException e) {
 
         assertTrue(failureLatch.await(AWAIT_CALLBACK_MS, TimeUnit.MILLISECONDS));
     }
+
+    @Test
+    public void testLoaderJsAssetPresence() throws IOException {
+        AssetManager assets = InstrumentationRegistry
+                .getInstrumentation()
+                .getTargetContext()
+                .getAssets();
+        assertNotNull(assets.open("hcaptcha/loader.js"));
+    }
+
+    @Test
+    public void testPolyfillsJsAssetPresence() throws IOException {
+        AssetManager assets = InstrumentationRegistry
+                .getInstrumentation()
+                .getTargetContext()
+                .getAssets();
+        assertNotNull(assets.open("hcaptcha/polyfills.js"));
+    }
 }