> Documentation index: https://firebase.google.com/support/llms.txt To review release notes for the Firebase console and for other Firebase platforms and related SDKs, refer to the [Firebase Release Notes](https://firebase.google.com/support/releases.md.txt). ## Version 4.23.0 - 11 November 2026 - Dropped support for Go version 1.25. The Admin Go SDK now requires Go 1.26 or higher. ### App Check - Added `VerifyOneTimeToken()` to verify and consume one-time App Check tokens for replay protection. ### Authentication - Validated `tenantID` and `providerID` URL path segments before constructing Authentication request paths. ## Version 4.22.0 - 23 September 2026 ### Cloud Messaging - Migrated the `SubscribeToTopic()` and `UnsubscribeFromTopic()` APIs on the messaging client from the legacy Instance ID API to the Cloud Messaging v1 topic subscription API. - Renamed the existing Instance ID based APIs to `SubscribeToTopicLegacy()` and `UnsubscribeFromTopicLegacy()`. These APIs are deprecated and will be removed in a future release. ## Version 4.21.0 - 8 July 2026 ### Cloud Messaging - Deprecated the `Token` field in `Message` type and the `Tokens` field in `MulticastMessage` type. Use the new `Fid` and `Fids` fields instead. - Added support for sending messages to Firebase installation IDs (FIDs) using the new `Fid` field in `Message` type and `Fids` field in `MulticastMessage` type. - Updated the `SendEachForMulticast()` and `SendEachForMulticastDryRun()` APIs to support both `Tokens` and `Fids` targets. ### Authentication - Added `VerifyAndChangeEmailLink()` and `VerifyAndChangeEmailLinkWithSettings()` APIs to generate out-of-band email action links for verifying and changing a user's email address. Thanks [utamori](https://github.com/utamori) for the [contribution](https://github.com/firebase/firebase-admin-go/pull/705). ## Version 4.20.0 - 14 May 2026 - Dropped support for Go versions 1.23 and 1.24. The Admin Go SDK now requires Go 1.25 or higher. ### Firebase Phone Number Verification - Added a new `VerifyToken()` API to verify Firebase Phone Number Verification tokens. ### Cloud Messaging - Added support for `BandwidthConstrainedOK` and `RestrictedSatelliteOK` fields in `AndroidConfig`. ## Version 4.19.0 - 21 January, 2026 ### Authentication - Added a new `QueryUsers()` API. This API enables searching for users with support for filtering and sorting, exposing the underlying `accounts:query` functionality. - Fixed an issue in the auth error code parser where extra whitespace in error messages caused known error codes to be incorrectly mapped to unknown errors. ### Cloud Firestore - Added support for multiple named databases. ## Version 4.18.0 - 31 July, 2025 ### Authentication - Updated `ActionCodeSettings` to support `LinkDomain`, allowing you to customize the Firebase Hosting domain used in email action flows. As part of this change, `DynamicLinkDomain` has been deprecated. Thanks [graeme-verticalscope](https://github.com/graeme-verticalscope) for the [contribution](https://github.com/firebase/firebase-admin-go/pull/703). ## Version 4.17.0 - 17 July, 2025 ### Cloud Messaging - Optimized sending of batch requests with a limited size worker pool. ### Remote Config - Added support for configuring Remote Config server applications. ## Version 4.16.1 - 11 June, 2025 - Correctly set minimum Go version to 1.23 in `go.mod`. Thanks [anuraaga](https://github.com/anuraaga) for the [contribution](https://github.com/firebase/firebase-admin-go/pull/699). ## Version 4.16.0 - 05 June, 2025 - Dropped support for Go versions 1.21 and 1.22. The Admin Go SDK now requires Go 1.23 or 1.24. ### Cloud Messaging - Added support for `Proxy` field in FCM `AndroidNotification`. Thanks [byungwoo-Nam](https://github.com/byungwoo-Nam) for the [contribution](https://github.com/firebase/firebase-admin-go/pull/676). - Added support for `LiveActivityToken` field in FCM `APNSConfig`. Thanks [morikuni](https://github.com/morikuni) for the [contribution](https://github.com/firebase/firebase-admin-go/pull/668). ## Version 4.15.2 - 13 February, 2025 - Updated the `cloud.google.com/go/firestore` dependency to v1.18.0 and the `cloud.google.com/go/storage` dependency to v1.49.0. ## Version 4.15.1 - 05 December, 2024 - Upgraded the `golang-jwt/jwt` dependency to v4.5.1. - Added metrics headers to outgoing HTTP requests. ## Version 4.15.0 - 24 October, 2024 - Dropped support for Go version 1.20. The Admin Go SDK now requires Go 1.21 or higher. ### Cloud Messaging - Added the `DirectBootOK` field to the `AndroidConfig` type. Thanks [akankshaJaiswal8](https://github.com/akankshaJaiswal8) for the [contribution](https://github.com/firebase/firebase-admin-go/pull/638). ## Version 4.14.1 - 30 May, 2024 ### Authentication - Fixed an issue that caused the `verifyIDToken()` and `verifyIDTokenAndCheckRevoked()` APIs to throw an error when the cache headers lacked expiry time for public certificates. ## Version 4.14.0 - 10 April, 2024 - Dropped support for Go versions 1.17, 1.18, and 1.19. The Admin Go SDK now requires Go 1.20 or higher. ### Cloud Messaging - Added the `FCMOptions` field to the `MulticastMessage` type. Thanks [FZambia](https://github.com/FZambia) for the [contribution](https://github.com/firebase/firebase-admin-go/pull/537). ## Version 4.13.0 - 23 November, 2023 ### Cloud Storage - Mapped Firebase `FIREBASE_STORAGE_EMULATOR_HOST` to Cloud API's `STORAGE_EMULATOR_HOST`. ### Authentication - Added the `TotpInfo` field to `UserRecord` type. ## Version 4.12.1 - 25 September, 2023 ### Authentication - Added support for updating multi-factor enrollments in the `UpdateUser()` API. Thanks [brokeyourbike](https://github.com/brokeyourbike) for the [contribution](https://github.com/firebase/firebase-admin-go/pull/530). ## Version 4.12.0 - 12 July, 2023 ### Cloud Messaging - Added `sendEach()` and `sendEachForMulticast()` APIs. - `sendAll()` and `sendMulticast()` APIs are now deprecated. Use `sendEach()` and `sendEachForMulticast()` APIs instead. ## Version 4.11.0 - 06 April, 2023 - The SDK now requires module mode to build the current version of the library. ### Authentication - Added `TOTP` as a multi-factor option in project and tenant configuration. ## Version 4.10.0 - 10 November, 2022 ### Realtime Database - The Realtime Database API now supports running against Firebase emulator suite. Enable the emulator mode by setting the `FIREBASE_DATABASE_EMULATOR_HOST` environment variable to point to the emulator Realtime Database endpoint. Thanks [r-LaForge](https://github.com/r-LaForge) for the [contribution](https://github.com/firebase/firebase-admin-go/pull/517). ### Firebase App Check - Added a new `app_check.verify_token()` API to verify App Check tokens. Thanks [bamnet](https://github.com/bamnet) for the [contribution](https://github.com/firebase/firebase-admin-go/pull/484). ## Version 4.9.0 - 06 October, 2022 - Dropped support for Go versions 1.15 and 1.16. Admin Go SDK now requires Go 1.17 or higher. ### Authentication - Fixed an incorrect key used to set `MemoryCost` config in `StandardScrypt` type. ## Version 4.8.0 - 06 April, 2022 - Dropped support for Go versions 1.11 to 1.14. The Admin Go SDK now requires Go 1.15 or higher. ### Authentication - Added support for enabling or disabling anonymous authentication through tenant configuration. Thanks [sonatard](https://github.com/sonatard) for the [contribution](https://github.com/firebase/firebase-admin-go/pull/412). ## Version 4.7.1 - 20 January, 2022 ### Authentication - Prevented serializing `unspecified` fields as empty strings in the `auth.UserProvider` type. ## Version 4.7.0 - 15 December, 2021 ### Authentication - Added support for configuring the authorization code flow for OIDC providers. ## Version 4.6.1 - 04 November, 2021 - The Admin SDK no longer retries RPCs that fail with HTTP 500 internal server errors. For certain services, retrying on HTTP 500 errors is not idempotent. The SDK will continue to retry RPCs that fail with HTTP 503 unavailable errors. ### Authentication - The `VerifyIDTokenAndCheckRevoked()` and `VerifySessionCookieAndCheckRevoked()` APIs now throw an error if the user record is disabled. ## Version 4.6.0 - 02 June, 2021 ### Authentication - The Admin SDK now supports ID token verification when operating in emulator mode. Thanks [maku693](https://github.com/maku693) for the [contribution](https://github.com/firebase/firebase-admin-go/pull/419). - Added a new `IsEmailNotFound()` error checking function for handling the errors returned by the email action link generator functions. - Fixed the ability to import users with partial user metadata. You can now import a user with only `CreationTimestamp` in `UserMetadata`. Thanks [valery-barysok](https://github.com/valery-barysok) for the [contribution](https://github.com/firebase/firebase-admin-go/pull/445). ### Cloud Messaging - Fixed an error with unmarshalling `AndroidNotificationPriority`. Thanks [parnic](https://github.com/parnic) for the [contribution](https://github.com/firebase/firebase-admin-go/pull/435). ### Realtime Database - Added support for Realtime Database instances hosted in non-US regions. Thanks [thameezb](https://github.com/thameezb) for the [contribution](https://github.com/firebase/firebase-admin-go/pull/423). ## Version 4.5.0 - 14 April, 2021 ### Authentication - Added multi-factor authentication info to the `UserRecord` type. Thanks [jasperkuperus](https://github.com/jasperkuperus) for the [contribution](https://github.com/firebase/firebase-admin-go/pull/422). ## Version 4.4.0 - 29 March, 2021 ### Authentication - Added a new `GetUserByProviderUID()` function to look up user accounts by their providers. - The `GetUserByProviderID()` function introduced in the previous release has been deprecated in favor of the new `GetUserByProviderUID()` function. ## Version 4.3.0 - 24 March, 2021 ### Authentication - The `UpdateUser()` function now supports linking a federated ID with a user account. - Added a new `GetUserByProviderID()` function to look up user accounts by their providers. ## Version 4.2.0 - 28 January, 2021 ### Authentication - The Admin SDK now supports the Authentication emulator. Developers can configure the SDK to run against the emulator by setting the `FIREBASE_AUTH_EMULATOR_HOST` environment variable. Thanks [maku693](https://github.com/maku693) for the [contribution](https://github.com/firebase/firebase-admin-go/pull/414). ## Version 4.1.0 - 22 October, 2020 ### Authentication - Implemented support for specifying password-salt order in hash configurations used when importing users. - Migrated the token signing functionality to the new IAM credentials API. ## Version 4.0.0 - 16 June, 2020 - The Admin SDK has opted into Go modules. The package name now has the major version appended to it. Developers should use the new package name `firebase.google.com/go/v4` when installing and importing the SDK. See the Go Admin SDK [v4 migration guide](https://firebase.google.com/docs/admin/migrate-go-v4.md.txt) for more details. - Added a new `errorutils` package that provides functions for checking for platform-level error codes. ### Authentication - Added new service-level error checking functions `IsIDTokenInvalid()`, `IsIDTokenExpired()`, `IsSessionCookieInvalid()`, `IsSessionCookieExpired()` and `IsCertificateFetchFailed()`. These functions can be used in conjunction with the existing JWT verification APIs. ### Cloud Messaging - The `messaging.WebpushFcmOptions` type has been renamed to `messaging.WebpushFCMOptions`. - Added new service-level error checking functions `IsThirdPartyAuthError()`, `IsQuotaExceeded()`, `IsSenderIDMismatch()`, `IsUnregistered()` and `IsUnavailable()`. ## Version 3.13.0 - 21 May, 2020 ### Authentication - Added `GetUsers()` and `DeleteUsers()` APIs for retrieving and deleting user accounts in bulk. - Implemented support for creating custom tokens scoped to specific tenants. `CustomToken()` and `CustomTokenWithClaims()` functions are now also exposed on the `auth.TenantClient` type. ## Version 3.12.1 - 23 April, 2020 - Deferred credential loading until required, which allows some APIs like `auth.VerifyIDToken()` to be called without credentials. ### Cloud Messaging - Updated the remote endpoint used by topic management operations. Thanks [rueian](https://github.com/rueian) for the [contribution](https://github.com/firebase/firebase-admin-go/pull/335). ## Version 3.12.0 - 15 January, 2020 ### Cloud Messaging - Introduced a series of new parameters to the [`AndroidNotification`](https://godoc.org/firebase.google.com/go/messaging#AndroidNotification) type. ### Authentication - Fixed a bug in the `TenantIterator` type which was preventing it from listing all the tenants correctly. ## Version 3.11.1 - 23 December, 2019 ### Authentication - Minor improvements to the implementation to fix the API reference output generated by `godoc`. ## Version 3.11.0 - 18 December, 2019 - Dropped support for Go 1.9 and 1.10. The Admin SDK for Go now requires Go 1.11 or higher. Thanks [shogo82148](https://github.com/shogo82148) for the [contribution](https://github.com/firebase/firebase-admin-go/pull/294). ### Authentication - Added a new `IsInvalidEmail()` error checking function. Thanks [shogo82148](https://github.com/shogo82148) for the [contribution](https://github.com/firebase/firebase-admin-go/pull/299). - Added `auth.TenantManager` API for creating, updating, retrieving, and deleting authentication tenants. - Added `auth.TenantClient` API for managing users, configuring SAML/OIDC providers, and generating email action links for specific tenants. ### Cloud Messaging - Batch messaging APIs `SendAll()` and `SendMulticast()` now support sending up to 500 messages in a single call. ## Version 3.10.0 - 30 October, 2019 ### Authentication - `auth.ExportedUserRecord` no longer exposes password hashes that are redacted due to lack of permissions in the service account credentials. - Added `auth.OIDCProviderConfig` type and the related functions to create, retrieve, update and delete OIDC auth provider configurations. - Added `auth.SAMLProviderConfig` type and the related functions to create, retrieve, update and delete SAML auth provider configurations. ### Cloud Messaging - Added support for sending an image URL with notifications. Thanks [chemidy](https://github.com/chemidy) for the [contribution](https://github.com/firebase/firebase-admin-go/pull/261). ## Version 3.9.0 - August 07, 2019 ### Cloud Messaging - Added the [`SendAll()`](https://godoc.org/firebase.google.com/go/messaging#Client.SendAll) API for sending multiple notifications as a batch. - Added `MulticastMessage` and [`SendMulticast()`](https://godoc.org/firebase.google.com/go/messaging#Client.SendMulticast) APIs for sending notifications to multiple recipients. - Added support for specifying the analytics label for notifications via `AndroidFCMOptions`, `APNSFCMOptions` and `FCMOptions` types. Thanks [chemidy](https://github.com/chemidy) for the [contribution](https://github.com/firebase/firebase-admin-go/pull/256). ## Version 3.8.1 - June 11, 2019 - Fixed some unit tests that were failing in environments without Google Application Default credentials. ## Version 3.8.0 - May 30, 2019 ### Authentication - Added APIs for creating links for password reset, email verification and email link sign-in via `auth.PasswordResetLink()`, `auth.EmailVerificationLink()` and `auth.EmailSignInLink()`. See [Generating Email Action Links](https://firebase.google.com/docs/auth/admin/email-action-links.md.txt) for more details and code samples. - All APIs in the `auth` package now automatically retry RPC calls failing due to I/O or HTTP errors. ## Version 3.7.0 - March 28, 2019 - Enabled automatic HTTP retries for the APIs in `db`, `messaging` and `iid` packages. ### Authentication - A new [`SessionCookie()`](https://godoc.org/firebase.google.com/go/auth#Client.SessionCookie) function for creating a [session cookie](https://firebase.google.com/docs/auth/admin/manage-cookies.md.txt) from a Firebase ID token. - A new [`VerifySessionCookie()`](https://godoc.org/firebase.google.com/go/auth#Client.VerifySessionCookie) function for validating a given session cookie string. ## Version 3.6.0 - January 16, 2019 ### Cloud Messaging - The [`messaging.Aps`](https://godoc.org/firebase.google.com/go/messaging#Aps) type now supports configuring a critical alert sound. A new [`messaging.CriticalSound`](https://godoc.org/firebase.google.com/go/messaging#CriticalSound) type has been introduced for this purpose. - Public types in the `messaging` package now support correct JSON unmarshalling. ### Authentication - The [`VerifyIDToken()`](https://godoc.org/firebase.google.com/go/auth#Client.VerifyIDToken) function now tolerates a clock skew of up to 5 minutes when comparing JWT timestamps. ## Version 3.5.0 - December 04, 2018 - Dropped support for Go 1.8 and earlier. ### Cloud Messaging - `messaging.AndroidNotification` type now supports specifying a `channel_id` when sending messages to Android O devices. Thanks [chemidy](https://github.com/chemidy) for the [contribution](https://github.com/firebase/firebase-admin-go/pull/202). - `messaging.ApsAlert` type now supports specifying a subtitle. Thanks [chemidy](https://github.com/chemidy) for the [contribution](https://github.com/firebase/firebase-admin-go/pull/191). - `messaging.WebpushNotification` type now supports specifying additional FCM options. Thanks [chemidy](https://github.com/chemidy) for the [contribution](https://github.com/firebase/firebase-admin-go/pull/185). - Improved error handling by requesting a more verbose error response from the FCM backend service. ### Realtime Database - Fixed how the SDK handles special characters in node names. ## Version 3.4.0 - September 13, 2018 ### Realtime Database - [`firebase.App`](https://godoc.org/firebase.google.com/go#App) provides a new `DatabaseWithURL()` function that can be used to initialize clients that connect to different database instances in the same Firebase project. ## Version 3.3.0 - August 9, 2018 ### Authentication - Fixed a regression introduced in the 3.2.0 release, where [`VerifyIDToken()`](https://godoc.org/firebase.google.com/go/auth#Client.VerifyIDToken) cannot be used in Google App Engine. ### Cloud Messaging - [`messaging.WebpushNotification`](https://godoc.org/firebase.google.com/go/messaging#WebpushNotification) type now supports arbitrary key-value pairs in its payload. ## Version 3.2.0 - July 17, 2018 - The Admin SDK can now read the Firebase/Google Cloud Platform project ID from both `GCLOUD_PROJECT` and `GOOGLE_CLOUD_PROJECT` environment variables. ### Authentication - The Admin SDK can now create custom tokens without being initialized with service account credentials. - The SDK now provides a [`ServiceAccountId`](https://godoc.org/firebase.google.com/go#Config) option specifier, which can be used to set just the client email of a service account. - When deployed in an environment managed by Google (e.g. Google App Engine), the SDK can auto discover a service account ID without any explicit configuration. ## Version 3.1.0 - June 12, 2018 - The `iid` package now provides a set of new functions for checking various error conditions such as `iid.IsInvalidArgument()`, `iid.IsNotFound()`, etc. ### Authentication - A new [`ImportUsers()`](https://godoc.org/firebase.google.com/go/auth#Client.ImportUsers) function for [importing users](https://firebase.google.com/docs/auth/admin/import-users.md.txt) to Firebase Auth in bulk. - `UpdateUser()` and `DeleteUser()` functions now correctly return a `UserNotFound` error when called with a non-existing user ID. ## Version 3.0.0 - May 8, 2018 - `CustomToken()`, `CustomTokenWithClaims()` and `VerifyIDToken()` functions now take a `Context` as the first argument. ## Version 2.7.0 - April 17, 2018 - The `auth` and `messaging` packages now provide a set of new functions for checking various error conditions (for example, `auth.IsIDTokenRevoked()`, `messaging.IsInvalidArgument()` etc). ### Cloud Messaging - Added the `MutableContent` field to the [`messaging.Aps`](https://godoc.org/firebase.google.com/go/messaging#Aps) type. This can be used to set the `mutable-content` property when sending FCM messages to APNs targets. - Added support for specifying arbitrary key-value fields in the `Aps` type. - Improved error handling in the [`messaging`](https://godoc.org/firebase.google.com/go/messaging) API. The returned errors now contain additional details. ## Version 2.6.1 - March 15, 2018 ### Cloud Messaging - Fixed a bug in the `UnsubscribeFromTopic()` function. Thanks [michaljemala](https://github.com/michaljemala) for the [contribution](https://github.com/firebase/firebase-admin-go/pull/114). ### Version support - Support for go version 1.6. ## Version 2.6.0 - February 28, 2018 ### Realtime Database - A new [`db`](https://godoc.org/firebase.google.com/go/db) package that facilitates basic data manipulation operations (create, read, update and delete), conditional updates (transactions) and advanced queries. Currently, this API does not support realtime event listeners. ## Version 2.5.0 - February 14, 2018 ### Cloud Messaging - A new [`messaging`](https://godoc.org/firebase.google.com/go/messaging) package for sending FCM messages and managing topic subscriptions. - A new [`Send()`](https://godoc.org/firebase.google.com/go/messaging#Client.Send) function for sending FCM messages. - A new [`SubscribeToTopic()`](https://godoc.org/firebase.google.com/go/messaging#Client.SubscribeToTopic) function for subscribing a list of device registration tokens to a FCM topic. - A new [`UnubscribeFromTopic()`](https://godoc.org/firebase.google.com/go/messaging#Client.UnsubscribeFromTopic) function for unsubscribing a list of device registration tokens from a FCM topic. ### Authentication - A new [`VerifyIDTokenAndCheckRevoked()`](https://godoc.org/firebase.google.com/go/auth#Client.VerifyIDToken) function to check for revoked ID tokens. - A new [`RevokeRefreshTokens()`](https://godoc.org/firebase.google.com/go/auth#Client.RevokeRefreshTokens) function to invalidate all refresh tokens issued to a user. - A new property `TokensValidAfterMillis` has been added to the [`auth.UserRecord`](https://godoc.org/firebase.google.com/go/auth#UserRecord) type. ## Version 2.4.0 - January 11, 2018 ### Initialization - The [`firebase.NewApp()`](https://godoc.org/firebase.google.com/go#NewApp) method can now be invoked without any arguments. This initializes an app using Google Application Default Credentials, and [`firebase.Config`](https://godoc.org/firebase.google.com/go#Config) loaded from the `FIREBASE_CONFIG` environment variable. ### Authentication - The user management operations in the `auth` package now uses the [`identitytoolkit/v3`](https://google.golang.org/api/identitytoolkit/v3) library. - The `ProviderID` field on the [`auth.UserRecord`](https://godoc.org/firebase.google.com/go/auth#UserRecord) type is now set to the constant value `firebase`. ## Version 2.3.0 - December 21, 2017 - A new [`InstanceID`](https://godoc.org/firebase.google.com/go#App.InstanceID) API that facilitates deleting instance IDs and associated user data from Firebase projects. ## Version 2.2.1 - December 13, 2017 ### Authentication - Adding the `X-Client-Version` to the headers in the API calls for tracking API usage. ## Version 2.2.0 - December 08, 2017 ### Authentication - A new user management API that supports querying and updating user accounts associated with a Firebase project. This adds `GetUser()`, `GetUserByEmail()`, `GetUserByPhoneNumber()`, `CreateUser()`, `UpdateUser()`, `DeleteUser()`, `Users()` and `SetCustomUserClaims()` functions to the [`auth.Client`](https://godoc.org/firebase.google.com/go/auth#Client) API. ## Version 2.1.0 - November 07, 2017 - A new [`Firestore` API](https://godoc.org/firebase.google.com/go#App.Firestore) that enables access to [Cloud Firestore](https://firebase.google.com/docs/firestore.md.txt) databases. ## Version 2.0.0 - October 13, 2017 - A new [Cloud Storage API](https://godoc.org/firebase.google.com/go/storage) that facilitates accessing Google Cloud Storage buckets using the [`cloud.google.com/go/storage`](https://cloud.google.com/go/storage) package. ### Authentication - The [`Auth()`](https://godoc.org/firebase.google.com/go#App.Auth) API now accepts a `Context` argument. This breaking change enables passing different contexts to different services, instead of using a single context per [`App`](https://godoc.org/firebase.google.com/go#App). ## Version 1.0.2 - September 13, 2017 ### Authentication - When deployed in the Google App Engine environment, the SDK can now leverage the utilities provided by the [App Engine SDK](https://cloud.google.com/appengine/docs/standard/go/reference) to sign JWT tokens. As a result, it is now possible to initialize the Admin SDK in App Engine without a service account JSON file, and still be able to call [`CustomToken()`](https://godoc.org/firebase.google.com/go/auth#Client.CustomToken) and [`CustomTokenWithClaims()`](https://godoc.org/firebase.google.com/go/auth#Client.CustomTokenWithClaims). ## Version 1.0.1 - September 07, 2017 ### Authentication - Now uses the client options provided during [SDK initialization](https://godoc.org/firebase.google.com/go#NewApp) to create the [`http.Client`](https://godoc.org/net/http#Client) that is used to fetch public key certificates. This enables developers to use the ID token verification feature in environments like Google App Engine by providing a platform-specific `http.Client` using [`option.WithHTTPClient()`](https://godoc.org/google.golang.org/api/option#WithHTTPClient). ## Version 1.0.0 - August 30, 2017 - Initial release of the Admin Go SDK. See [Add the Firebase Admin SDK to your Server](https://firebase.google.com/docs/admin/setup.md.txt) to get started. - You can configure the SDK to use service account credentials, user credentials (refresh tokens), or Google Cloud application default credentials to access your Firebase project. ### Authentication - The initial release includes the `CustomToken()`, `CustomTokenWithClaims()`, and `VerifyIDToken()` functions for minting custom authentication tokens and verifying Firebase ID tokens.