diff --git a/auth-next/index.js b/auth-next/index.js
index 73d33219..c4dadfe0 100644
--- a/auth-next/index.js
+++ b/auth-next/index.js
@@ -26,7 +26,7 @@ function makeFacebookCredential(response) {
 function makeEmailCredential(email, password) {
   // [START auth_make_email_credential]
   const { EmailAuthProvider } = require("firebase/auth");
-  
+
   const credential = EmailAuthProvider.credential(email, password);
   // [END auth_make_email_credential]
 }
@@ -121,3 +121,17 @@ function signInRedirect(provider) {
   signInWithRedirect(auth, provider);
   // [END auth_signin_redirect]
 }
+
+function initializeWithCustomDomain() {
+  // [START auth_init_custom_domain]
+  const { initializeApp } = require("firebase/app");
+
+  const firebaseConfig = {
+    apiKey: "...",
+    // By default, authDomain is '[YOUR_APP].firebaseapp.com'.
+    // You may replace it with a custom domain.
+    authDomain: '[YOUR_CUSTOM_DOMAIN]'
+  };
+  const firebaseApp = initializeApp(firebaseConfig);
+  // [END auth_init_custom_domain]
+}
diff --git a/auth/index.js b/auth/index.js
index 6ea5d587..6567c030 100644
--- a/auth/index.js
+++ b/auth/index.js
@@ -101,3 +101,14 @@ function signInRedirect(provider) {
   firebase.auth().signInWithRedirect(provider);
   // [END auth_signin_redirect]
 }
+
+function initializeWithCustomDomain() {
+  // [START auth_init_custom_domain]
+  firebase.initializeApp({
+    apiKey: '...',
+    // By default, authDomain is '[YOUR_APP].firebaseapp.com'.
+    // You may replace it with a custom domain.
+    authDomain: '[YOUR_CUSTOM_DOMAIN]'
+  });
+  // [END auth_init_custom_domain]
+}
diff --git a/auth/oidc.js b/auth/oidc.js
index 4c056e52..e3a3e01e 100644
--- a/auth/oidc.js
+++ b/auth/oidc.js
@@ -4,9 +4,6 @@
 import firebase from "firebase/app";
 import "firebase/auth";
 
-// [SNIPPET_REGISTRY disabled]
-// [SNIPPETS_SEPARATION enabled]
-
 function oidcProvider() {
   // [START auth_oidc_provider_create]
   const provider = new firebase.auth.OAuthProvider('oidc.myProvider');
diff --git a/auth/saml.js b/auth/saml.js
index a55b691c..e3a99cde 100644
--- a/auth/saml.js
+++ b/auth/saml.js
@@ -4,9 +4,6 @@
 import firebase from "firebase/app";
 import "firebase/auth";
 
-// [SNIPPET_REGISTRY disabled]
-// [SNIPPETS_SEPARATION enabled]
-
 function samlProvider() {
   // [START auth_saml_provider_create]
   const provider = new firebase.auth.SAMLAuthProvider('saml.myProvider');
diff --git a/snippets/auth-next/index/auth_init_custom_domain.js b/snippets/auth-next/index/auth_init_custom_domain.js
new file mode 100644
index 00000000..971e5c56
--- /dev/null
+++ b/snippets/auth-next/index/auth_init_custom_domain.js
@@ -0,0 +1,17 @@
+// This snippet file was generated by processing the source file:
+// ./auth-next/index.js
+//
+// To update the snippets in this file, edit the source and then run
+// 'npm run snippets'.
+
+// [START auth_init_custom_domain_modular]
+import { initializeApp } from "firebase/app";
+
+const firebaseConfig = {
+  apiKey: "...",
+  // By default, authDomain is '[YOUR_APP].firebaseapp.com'.
+  // You may replace it with a custom domain.
+  authDomain: '[YOUR_CUSTOM_DOMAIN]'
+};
+const firebaseApp = initializeApp(firebaseConfig);
+// [END auth_init_custom_domain_modular]
\ No newline at end of file
diff --git a/snippets/auth/oidc/auth_oidc_direct_sign_in.js b/snippets/auth/oidc/auth_oidc_direct_sign_in.js
deleted file mode 100644
index 5a0c629d..00000000
--- a/snippets/auth/oidc/auth_oidc_direct_sign_in.js
+++ /dev/null
@@ -1,19 +0,0 @@
-// This snippet file was generated by processing the source file:
-// ./auth/oidc.js
-//
-// To update the snippets in this file, edit the source and then run
-// 'npm run snippets'.
-
-// [START auth_oidc_direct_sign_in_modular]
-const credential = provider.credential(oidcIdToken, null);
-
-firebase.auth().signInWithCredential(credential)
-  .then((result) => {
-    // User is signed in.
-    // User now has a odic.myProvider UserInfo in providerData.
-  })
-  .catch((error) => {
-    // Handle / display error.
-    // ...
-  });
-// [END auth_oidc_direct_sign_in_modular]
\ No newline at end of file
diff --git a/snippets/auth/oidc/auth_oidc_provider_create.js b/snippets/auth/oidc/auth_oidc_provider_create.js
deleted file mode 100644
index 09e08ad8..00000000
--- a/snippets/auth/oidc/auth_oidc_provider_create.js
+++ /dev/null
@@ -1,9 +0,0 @@
-// This snippet file was generated by processing the source file:
-// ./auth/oidc.js
-//
-// To update the snippets in this file, edit the source and then run
-// 'npm run snippets'.
-
-// [START auth_oidc_provider_create_modular]
-const provider = new firebase.auth.OAuthProvider('oidc.myProvider');
-// [END auth_oidc_provider_create_modular]
\ No newline at end of file
diff --git a/snippets/auth/oidc/auth_oidc_signin_popup.js b/snippets/auth/oidc/auth_oidc_signin_popup.js
deleted file mode 100644
index c5ff4afa..00000000
--- a/snippets/auth/oidc/auth_oidc_signin_popup.js
+++ /dev/null
@@ -1,18 +0,0 @@
-// This snippet file was generated by processing the source file:
-// ./auth/oidc.js
-//
-// To update the snippets in this file, edit the source and then run
-// 'npm run snippets'.
-
-// [START auth_oidc_signin_popup_modular]
-firebase.auth().signInWithPopup(provider)
-  .then((result) => {
-    // User is signed in.
-    // result.credential is a firebase.auth().OAuthCredential object.
-    // result.credential.providerId is equal to 'oidc.myProvider'.
-    // result.credential.idToken is the OIDC provider's ID token.
-  })
-  .catch((error) => {
-    // Handle error.
-  });
-// [END auth_oidc_signin_popup_modular]
\ No newline at end of file
diff --git a/snippets/auth/oidc/auth_oidc_signin_redirect.js b/snippets/auth/oidc/auth_oidc_signin_redirect.js
deleted file mode 100644
index 4951c4bf..00000000
--- a/snippets/auth/oidc/auth_oidc_signin_redirect.js
+++ /dev/null
@@ -1,11 +0,0 @@
-// This snippet file was generated by processing the source file:
-// ./auth/oidc.js
-//
-// To update the snippets in this file, edit the source and then run
-// 'npm run snippets'.
-
-// [START auth_oidc_signin_redirect_modular]
-firebase.auth().signInWithRedirect(provider).catch((error) => {
-  // Handle error.
-});
-// [END auth_oidc_signin_redirect_modular]
\ No newline at end of file
diff --git a/snippets/auth/oidc/auth_oidc_signin_redirect_result.js b/snippets/auth/oidc/auth_oidc_signin_redirect_result.js
deleted file mode 100644
index 2cd0eaa7..00000000
--- a/snippets/auth/oidc/auth_oidc_signin_redirect_result.js
+++ /dev/null
@@ -1,20 +0,0 @@
-// This snippet file was generated by processing the source file:
-// ./auth/oidc.js
-//
-// To update the snippets in this file, edit the source and then run
-// 'npm run snippets'.
-
-// [START auth_oidc_signin_redirect_result_modular]
-// On return.
-firebase.auth().getRedirectResult()
-  .then((result) => {
-    // User is signed in.
-    // result.credential is a firebase.auth().OAuthCredential object.
-    // result.credential.providerId is equal to 'oidc.myProvider'.
-    // result.credential.idToken is the OIDC provider's ID token.
-  })
-  .catch((error) => {
-    // Handle / display error.
-    // ...
-  });
-// [END auth_oidc_signin_redirect_result_modular]
\ No newline at end of file
diff --git a/snippets/auth/saml/auth_saml_provider_create.js b/snippets/auth/saml/auth_saml_provider_create.js
deleted file mode 100644
index a9765e5e..00000000
--- a/snippets/auth/saml/auth_saml_provider_create.js
+++ /dev/null
@@ -1,9 +0,0 @@
-// This snippet file was generated by processing the source file:
-// ./auth/saml.js
-//
-// To update the snippets in this file, edit the source and then run
-// 'npm run snippets'.
-
-// [START auth_saml_provider_create_modular]
-const provider = new firebase.auth.SAMLAuthProvider('saml.myProvider');
-// [END auth_saml_provider_create_modular]
\ No newline at end of file
diff --git a/snippets/auth/saml/auth_saml_signin_popup.js b/snippets/auth/saml/auth_saml_signin_popup.js
deleted file mode 100644
index 1fb3b4f6..00000000
--- a/snippets/auth/saml/auth_saml_signin_popup.js
+++ /dev/null
@@ -1,21 +0,0 @@
-// This snippet file was generated by processing the source file:
-// ./auth/saml.js
-//
-// To update the snippets in this file, edit the source and then run
-// 'npm run snippets'.
-
-// [START auth_saml_signin_popup_modular]
-firebase.auth().signInWithPopup(provider)
-  .then((result) => {
-    // User is signed in.
-    // Identity provider data available in result.additionalUserInfo.profile,
-    // or from the user's ID token obtained from result.user.getIdToken()
-    // as an object in the firebase.sign_in_attributes custom claim
-    // This is also available from result.user.getIdTokenResult()
-    // idTokenResult.claims.firebase.sign_in_attributes.
-  })
-  .catch((error) => {
-    // Handle / display error.
-    // ...
-  });
-// [END auth_saml_signin_popup_modular]
\ No newline at end of file
diff --git a/snippets/auth/saml/auth_saml_signin_redirect.js b/snippets/auth/saml/auth_saml_signin_redirect.js
deleted file mode 100644
index bd328a57..00000000
--- a/snippets/auth/saml/auth_saml_signin_redirect.js
+++ /dev/null
@@ -1,9 +0,0 @@
-// This snippet file was generated by processing the source file:
-// ./auth/saml.js
-//
-// To update the snippets in this file, edit the source and then run
-// 'npm run snippets'.
-
-// [START auth_saml_signin_redirect_modular]
-firebase.auth().signInWithRedirect(provider);
-// [END auth_saml_signin_redirect_modular]
\ No newline at end of file
diff --git a/snippets/auth/saml/auth_saml_signin_redirect_result.js b/snippets/auth/saml/auth_saml_signin_redirect_result.js
deleted file mode 100644
index 65a9f38b..00000000
--- a/snippets/auth/saml/auth_saml_signin_redirect_result.js
+++ /dev/null
@@ -1,20 +0,0 @@
-// This snippet file was generated by processing the source file:
-// ./auth/saml.js
-//
-// To update the snippets in this file, edit the source and then run
-// 'npm run snippets'.
-
-// [START auth_saml_signin_redirect_result_modular]
-firebase.auth().getRedirectResult()
-  .then((result) => {
-    // User is signed in.
-    // Provider data available in result.additionalUserInfo.profile,
-    // or from the user's ID token obtained from result.user.getIdToken()
-    // as an object in the firebase.sign_in_attributes custom claim
-    // This is also available from result.user.getIdTokenResult()
-    // idTokenResult.claims.firebase.sign_in_attributes.
-  }).catch((error) => {
-    // Handle / display error.
-    // ...
-  });
-// [END auth_saml_signin_redirect_result_modular]
\ No newline at end of file