diff --git a/etc/firebase-admin.app.api.md b/etc/firebase-admin.app.api.md
index 96c5a4ea55..08d145df0c 100644
--- a/etc/firebase-admin.app.api.md
+++ b/etc/firebase-admin.app.api.md
@@ -37,6 +37,20 @@ export interface Credential {
 // @public (undocumented)
 export function deleteApp(app: App): Promise<void>;
 
+// @public
+export interface FirebaseArrayIndexError {
+    error: FirebaseError;
+    index: number;
+}
+
+// @public
+export interface FirebaseError {
+    code: string;
+    message: string;
+    stack?: string;
+    toJSON(): object;
+}
+
 // @public (undocumented)
 export function getApp(name?: string): App;
 
diff --git a/src/app/core.ts b/src/app/core.ts
index 397ce189a5..c234b2875f 100644
--- a/src/app/core.ts
+++ b/src/app/core.ts
@@ -123,3 +123,82 @@ export interface App {
    */
   options: AppOptions;
 }
+
+/**
+ * `FirebaseError` is a subclass of the standard JavaScript `Error` object. In
+ * addition to a message string and stack trace, it contains a string code.
+ */
+export interface FirebaseError {
+
+  /**
+   * Error codes are strings using the following format: `"service/string-code"`.
+   * Some examples include `"auth/invalid-uid"` and
+   * `"messaging/invalid-recipient"`.
+   *
+   * While the message for a given error can change, the code will remain the same
+   * between backward-compatible versions of the Firebase SDK.
+   */
+  code: string;
+
+  /**
+   * An explanatory message for the error that just occurred.
+   *
+   * This message is designed to be helpful to you, the developer. Because
+   * it generally does not convey meaningful information to end users,
+   * this message should not be displayed in your application.
+   */
+  message: string;
+
+  /**
+   * A string value containing the execution backtrace when the error originally
+   * occurred.
+   *
+   * This information can be useful to you and can be sent to
+   * {@link https://firebase.google.com/support/ Firebase Support} to help
+   * explain the cause of an error.
+   */
+  stack?: string;
+
+  /**
+   * @return A JSON-serializable representation of this object.
+   */
+  toJSON(): object;
+}
+
+/**
+ * Composite type which includes both a `FirebaseError` object and an index
+ * which can be used to get the errored item.
+ *
+ * @example
+ * ```javascript
+ * var registrationTokens = [token1, token2, token3];
+ * admin.messaging().subscribeToTopic(registrationTokens, 'topic-name')
+ *   .then(function(response) {
+ *     if (response.failureCount > 0) {
+ *       console.log("Following devices unsucessfully subscribed to topic:");
+ *       response.errors.forEach(function(error) {
+ *         var invalidToken = registrationTokens[error.index];
+ *         console.log(invalidToken, error.error);
+ *       });
+ *     } else {
+ *       console.log("All devices successfully subscribed to topic:", response);
+ *     }
+ *   })
+ *   .catch(function(error) {
+ *     console.log("Error subscribing to topic:", error);
+ *   });
+ *```
+ */
+export interface FirebaseArrayIndexError {
+
+  /**
+   * The index of the errored item within the original array passed as part of the
+   * called API method.
+   */
+  index: number;
+
+  /**
+   * The error object.
+   */
+  error: FirebaseError;
+}
diff --git a/src/app/index.ts b/src/app/index.ts
index 9aeef5b363..e343e4fac2 100644
--- a/src/app/index.ts
+++ b/src/app/index.ts
@@ -17,7 +17,7 @@
 
 import { getSdkVersion } from '../utils';
 
-export { App, AppOptions } from './core'
+export { App, AppOptions, FirebaseArrayIndexError, FirebaseError } from './core'
 export { initializeApp, getApp, getApps, deleteApp } from './lifecycle';
 
 export { Credential, ServiceAccount, GoogleOAuthAccessToken } from './credential';
diff --git a/src/auth/user-import-builder.ts b/src/auth/user-import-builder.ts
index 72faa5304e..c0e151abaa 100644
--- a/src/auth/user-import-builder.ts
+++ b/src/auth/user-import-builder.ts
@@ -14,11 +14,11 @@
  * limitations under the License.
  */
 
+import { FirebaseArrayIndexError } from '../app/index';
 import { deepCopy, deepExtend } from '../utils/deep-copy';
 import * as utils from '../utils';
 import * as validator from '../utils/validator';
 import { AuthClientErrorCode, FirebaseAuthError } from '../utils/error';
-import { FirebaseArrayIndexError } from '../firebase-namespace-api';
 import {
   UpdateMultiFactorInfoRequest, UpdatePhoneMultiFactorInfoRequest, MultiFactorUpdateSettings
 } from './auth-config';
diff --git a/src/firebase-namespace-api.ts b/src/firebase-namespace-api.ts
index 9a56547118..798d8c426c 100644
--- a/src/firebase-namespace-api.ts
+++ b/src/firebase-namespace-api.ts
@@ -29,85 +29,6 @@ import { App as AppCore, AppOptions } from './app/index';
 
 export * from './app/index';
 
-/**
- * `FirebaseError` is a subclass of the standard JavaScript `Error` object. In
- * addition to a message string and stack trace, it contains a string code.
- */
-export interface FirebaseError {
-
-  /**
-   * Error codes are strings using the following format: `"service/string-code"`.
-   * Some examples include `"auth/invalid-uid"` and
-   * `"messaging/invalid-recipient"`.
-   *
-   * While the message for a given error can change, the code will remain the same
-   * between backward-compatible versions of the Firebase SDK.
-   */
-  code: string;
-
-  /**
-   * An explanatory message for the error that just occurred.
-   *
-   * This message is designed to be helpful to you, the developer. Because
-   * it generally does not convey meaningful information to end users,
-   * this message should not be displayed in your application.
-   */
-  message: string;
-
-  /**
-   * A string value containing the execution backtrace when the error originally
-   * occurred.
-   *
-   * This information can be useful to you and can be sent to
-   * {@link https://firebase.google.com/support/ Firebase Support} to help
-   * explain the cause of an error.
-   */
-  stack?: string;
-
-  /**
-   * @return A JSON-serializable representation of this object.
-   */
-  toJSON(): object;
-}
-
-/**
- * Composite type which includes both a `FirebaseError` object and an index
- * which can be used to get the errored item.
- *
- * @example
- * ```javascript
- * var registrationTokens = [token1, token2, token3];
- * admin.messaging().subscribeToTopic(registrationTokens, 'topic-name')
- *   .then(function(response) {
- *     if (response.failureCount > 0) {
- *       console.log("Following devices unsucessfully subscribed to topic:");
- *       response.errors.forEach(function(error) {
- *         var invalidToken = registrationTokens[error.index];
- *         console.log(invalidToken, error.error);
- *       });
- *     } else {
- *       console.log("All devices successfully subscribed to topic:", response);
- *     }
- *   })
- *   .catch(function(error) {
- *     console.log("Error subscribing to topic:", error);
- *   });
- *```
- */
-export interface FirebaseArrayIndexError {
-
-  /**
-   * The index of the errored item within the original array passed as part of the
-   * called API method.
-   */
-  index: number;
-
-  /**
-   * The error object.
-   */
-  error: FirebaseError;
-}
-
 // eslint-disable-next-line @typescript-eslint/no-namespace
 export namespace app {
   /**
diff --git a/src/messaging/messaging-api.ts b/src/messaging/messaging-api.ts
index 44c68e66eb..e586ba039d 100644
--- a/src/messaging/messaging-api.ts
+++ b/src/messaging/messaging-api.ts
@@ -15,7 +15,7 @@
  * limitations under the License.
  */
 
-import { FirebaseArrayIndexError, FirebaseError } from '../firebase-namespace-api';
+import { FirebaseArrayIndexError, FirebaseError } from '../app/index';
 
 export interface BaseMessage {
   data?: { [key: string]: string };
diff --git a/test/unit/auth/auth.spec.ts b/test/unit/auth/auth.spec.ts
index 406d1c7ee7..d896e75f20 100644
--- a/test/unit/auth/auth.spec.ts
+++ b/test/unit/auth/auth.spec.ts
@@ -27,8 +27,6 @@ import * as chaiAsPromised from 'chai-as-promised';
 import * as utils from '../utils';
 import * as mocks from '../../resources/mocks';
 
-import { Auth, TenantAwareAuth, BaseAuth } from '../../../src/auth/index';
-import { UserRecord } from '../../../src/auth/user-record';
 import { FirebaseApp } from '../../../src/app/firebase-app';
 import {
   AuthRequestHandler, TenantAwareAuthRequestHandler, AbstractAuthRequestHandler,
@@ -41,10 +39,12 @@ import {
   OIDCConfig, SAMLConfig, OIDCConfigServerResponse, SAMLConfigServerResponse,
 } from '../../../src/auth/auth-config';
 import { deepCopy } from '../../../src/utils/deep-copy';
-import { TenantManager } from '../../../src/auth/tenant-manager';
 import { ServiceAccountCredential } from '../../../src/app/credential-internal';
 import { HttpClient } from '../../../src/utils/api-request';
-import { DecodedIdToken, UpdateRequest, AuthProviderConfigFilter } from '../../../src/auth/index';
+import {
+  Auth, TenantAwareAuth, BaseAuth, UserRecord, DecodedIdToken,
+  UpdateRequest, AuthProviderConfigFilter, TenantManager,
+} from '../../../src/auth/index';
 
 chai.should();
 chai.use(sinonChai);
diff --git a/test/unit/auth/tenant-manager.spec.ts b/test/unit/auth/tenant-manager.spec.ts
index b769d236b0..720ba32b01 100644
--- a/test/unit/auth/tenant-manager.spec.ts
+++ b/test/unit/auth/tenant-manager.spec.ts
@@ -25,11 +25,10 @@ import * as chaiAsPromised from 'chai-as-promised';
 import * as mocks from '../../resources/mocks';
 import { FirebaseApp } from '../../../src/app/firebase-app';
 import { AuthRequestHandler } from '../../../src/auth/auth-api-request';
-import { Tenant, TenantServerResponse } from '../../../src/auth/tenant';
-import { TenantManager } from '../../../src/auth/tenant-manager';
+import { TenantServerResponse } from '../../../src/auth/tenant';
 import { AuthClientErrorCode, FirebaseAuthError } from '../../../src/utils/error';
 import {
-  CreateTenantRequest, UpdateTenantRequest, ListTenantsResult,
+  CreateTenantRequest, UpdateTenantRequest, ListTenantsResult, Tenant, TenantManager,
 } from '../../../src/auth/index';
 
 chai.should();
diff --git a/test/unit/auth/tenant.spec.ts b/test/unit/auth/tenant.spec.ts
index 31370e17bc..fbb94d3b23 100644
--- a/test/unit/auth/tenant.spec.ts
+++ b/test/unit/auth/tenant.spec.ts
@@ -21,9 +21,9 @@ import * as chaiAsPromised from 'chai-as-promised';
 
 import { deepCopy } from '../../../src/utils/deep-copy';
 import { EmailSignInConfig, MultiFactorAuthConfig } from '../../../src/auth/auth-config';
-import { Tenant, TenantServerResponse } from '../../../src/auth/tenant';
+import { TenantServerResponse } from '../../../src/auth/tenant';
 import {
-  CreateTenantRequest, UpdateTenantRequest, EmailSignInProviderConfig,
+  CreateTenantRequest, UpdateTenantRequest, EmailSignInProviderConfig, Tenant,
 } from '../../../src/auth/index';
 
 chai.should();
diff --git a/test/unit/instance-id/instance-id.spec.ts b/test/unit/instance-id/instance-id.spec.ts
index 90bbacdb8d..e6669c7fa8 100644
--- a/test/unit/instance-id/instance-id.spec.ts
+++ b/test/unit/instance-id/instance-id.spec.ts
@@ -26,7 +26,7 @@ import * as chaiAsPromised from 'chai-as-promised';
 import * as utils from '../utils';
 import * as mocks from '../../resources/mocks';
 
-import { InstanceId } from '../../../src/instance-id/instance-id';
+import { InstanceId } from '../../../src/instance-id/index';
 import { FirebaseInstanceIdRequestHandler } from '../../../src/instance-id/instance-id-request-internal';
 import { FirebaseApp } from '../../../src/app/firebase-app';
 import { FirebaseInstanceIdError, InstanceIdClientErrorCode } from '../../../src/utils/error';
diff --git a/test/unit/messaging/messaging.spec.ts b/test/unit/messaging/messaging.spec.ts
index b322030a18..3277edeefe 100644
--- a/test/unit/messaging/messaging.spec.ts
+++ b/test/unit/messaging/messaging.spec.ts
@@ -31,9 +31,8 @@ import { FirebaseApp } from '../../../src/app/firebase-app';
 import {
   Message, MessagingOptions, MessagingPayload, MessagingDevicesResponse,
   MessagingDeviceGroupResponse, MessagingTopicManagementResponse, BatchResponse,
-  SendResponse, MulticastMessage,
+  SendResponse, MulticastMessage, Messaging,
 } from '../../../src/messaging/index';
-import { Messaging } from '../../../src/messaging/messaging';
 import { BLACKLISTED_OPTIONS_KEYS, BLACKLISTED_DATA_PAYLOAD_KEYS } from '../../../src/messaging/messaging-internal';
 import { HttpClient } from '../../../src/utils/api-request';
 import { getSdkVersion } from '../../../src/utils/index';
diff --git a/test/unit/remote-config/remote-config-api-client.spec.ts b/test/unit/remote-config/remote-config-api-client.spec.ts
index 2d982e8808..70ca7bae97 100644
--- a/test/unit/remote-config/remote-config-api-client.spec.ts
+++ b/test/unit/remote-config/remote-config-api-client.spec.ts
@@ -19,7 +19,6 @@
 import * as _ from 'lodash';
 import * as chai from 'chai';
 import * as sinon from 'sinon';
-import { remoteConfig } from '../../../src/remote-config/index';
 import {
   FirebaseRemoteConfigError,
   RemoteConfigApiClient
@@ -31,10 +30,9 @@ import { FirebaseAppError } from '../../../src/utils/error';
 import { FirebaseApp } from '../../../src/app/firebase-app';
 import { deepCopy } from '../../../src/utils/deep-copy';
 import { getSdkVersion } from '../../../src/utils/index';
-
-import RemoteConfigTemplate = remoteConfig.RemoteConfigTemplate;
-import Version = remoteConfig.Version;
-import ListVersionsResult = remoteConfig.ListVersionsResult;
+import {
+  RemoteConfigTemplate, Version, ListVersionsResult,
+} from '../../../src/remote-config/index';
 
 const expect = chai.expect;
 
diff --git a/test/unit/storage/storage.spec.ts b/test/unit/storage/storage.spec.ts
index 80cb49ab92..5f59250930 100644
--- a/test/unit/storage/storage.spec.ts
+++ b/test/unit/storage/storage.spec.ts
@@ -22,7 +22,7 @@ import { expect } from 'chai';
 
 import * as mocks from '../../resources/mocks';
 import { FirebaseApp } from '../../../src/app/firebase-app';
-import { Storage } from '../../../src/storage/storage';
+import { Storage } from '../../../src/storage/index';
 
 describe('Storage', () => {
   let mockApp: FirebaseApp;