How do I set up Firebase Kotlin SDK for iOS in a Kotlin Multiplatform project?

You need to manually link the official Firebase iOS SDK via Cocoapods or Swift Package Manager, as the README specifies adding a cocoapods block in your Gradle file for pods like FirebaseCore. This adds extra configuration compared to Android.

Firebase Kotlin SDK vs official Firebase Android SDK KTX: which is better?

The Firebase Kotlin SDK is superior for multiplatform projects due to its coroutine-based API and cross-platform support, but for Android-only apps, the official KTX offers more mature, Google-maintained integration with full feature parity. The Kotlin SDK aims for compatibility but adds multiplatform overhead.

How to handle Firestore serialization with sealed classes in this SDK?

Mark your sealed class and its children as @Serializable, and the SDK automatically handles polymorphic serialization using a type property. You can customize this with @FirebaseClassDiscriminator, as explained in the README's serialization section.

Does Firebase Kotlin SDK support all Firebase services for web development?

It supports JS targets, but coverage varies by service; for example, Cloud Storage has 40% API coverage. You'll need to check the README's coverage table and may need to use underlying SDK access via .js properties for missing features.

What happens if I need a Firebase feature not covered by this SDK?

You can access the underlying official Firebase SDK using platform-specific extension properties (.android, .ios, .js) in your code, but this breaks multiplatform sharing and requires platform-specific implementations, as noted in the README.

How to contribute to increasing API coverage in Firebase Kotlin SDK?

Create an issue on GitHub using the provided template or submit a PR, following the contribution guidelines that include running tests with the Firebase emulator and maintaining API compatibility, as detailed in the Contributing section.

firebase-kotlin-sdk — Kotlin Multiplatform Firebase SDK

What is firebase-kotlin-sdk?

Firebase Kotlin SDK is a Kotlin-first SDK for Firebase that provides idiomatic Kotlin APIs for Firebase services. It solves the problem of using Firebase in multiplatform projects by enabling developers to write shared code for iOS, Android, Desktop, and Web, using modern Kotlin features like coroutines and Flows.

Target Audience

Kotlin developers building cross-platform applications with Firebase, especially those using Kotlin Multiplatform or Compose Multiplatform who need a unified Firebase API across mobile, desktop, and web targets.

Value Proposition

Developers choose this SDK for its Kotlin-first design, multiplatform support, and seamless integration with Kotlin features like coroutines and serialization, reducing boilerplate and providing a consistent experience across platforms compared to using separate Firebase SDKs.

A Kotlin-first SDK for Firebase

Use Cases

Best For

Building cross-platform mobile apps with shared Firebase logic
Using Firebase as a backend for Compose Multiplatform applications
Writing idiomatic Kotlin code with coroutines and Flows for Firebase operations
Sharing authentication and data layer code across iOS and Android
Developing desktop applications with Firebase services
Creating web applications with Firebase using Kotlin/JS

Not Ideal For

Projects requiring comprehensive API coverage for services like Cloud Messaging (1% coverage) or Remote Config (20% coverage), where critical features may be missing.
Teams building single-platform applications (e.g., Android-only) where the official Firebase SDK offers better native integration and full feature support without multiplatform overhead.
Developers who prefer or are locked into callback-based asynchronous patterns, as this SDK mandates the use of Kotlin coroutines and Flows.
Applications that depend on immediate access to the latest Firebase features, as this community-maintained SDK may lag behind official releases.

Pros & Cons

Pros

Modern Asynchronous API

Uses suspending functions and Flows instead of callbacks or platform-specific types like Task, providing a coroutine-based approach that eliminates callback hell, as shown in the README examples for Auth and Firestore.

True Multiplatform Support

Provides a common API binding to official Firebase SDKs for iOS, Android, JVM, and JS, enabling shared code across all targets—ideal for Compose Multiplatform apps, as stated in the project description.

Seamless Kotlin Serialization

Integrates Kotlinx Serialization for reading and writing custom classes to Firestore and Realtime Database, with built-in support for polymorphic serialization, server timestamps, and custom serializers, detailed in the serialization section.

Reduced Boilerplate

Employs default arguments, infix notation, and operator overloading to simplify APIs, replacing builder patterns from the official SDKs—evidenced by the cleaner updateProfile and query examples in the README.

Cons

Incomplete API Coverage

The README admits low coverage percentages for key services (e.g., Cloud Messaging at 1%, Remote Config at 20%), which can block development of features relying on these Firebase products.

Platform-Specific Setup Complexity

For iOS, developers must manually link Firebase SDKs via Cocoapods or SPM, and for JVM, additional initialization is required compared to official SDKs, adding friction to the setup process.

Community-Maintained Risks

As an open-source project maintained by volunteers, updates may be slower, and support less immediate than with official Firebase SDKs, potentially impacting bug fixes and new feature adoption.

Frequently Asked Questions

What is firebase-kotlin-sdk?

Target Audience

Value Proposition

Use Cases

Best For

Building cross-platform mobile apps with shared Firebase logic
Using Firebase as a backend for Compose Multiplatform applications
Writing idiomatic Kotlin code with coroutines and Flows for Firebase operations
Sharing authentication and data layer code across iOS and Android
Developing desktop applications with Firebase services
Creating web applications with Firebase using Kotlin/JS

Not Ideal For

Projects requiring comprehensive API coverage for services like Cloud Messaging (1% coverage) or Remote Config (20% coverage), where critical features may be missing.
Teams building single-platform applications (e.g., Android-only) where the official Firebase SDK offers better native integration and full feature support without multiplatform overhead.
Developers who prefer or are locked into callback-based asynchronous patterns, as this SDK mandates the use of Kotlin coroutines and Flows.
Applications that depend on immediate access to the latest Firebase features, as this community-maintained SDK may lag behind official releases.

Pros & Cons

Pros

Modern Asynchronous API

True Multiplatform Support

Seamless Kotlin Serialization

Reduced Boilerplate

Cons

Incomplete API Coverage

The README admits low coverage percentages for key services (e.g., Cloud Messaging at 1%, Remote Config at 20%), which can block development of features relying on these Firebase products.

Platform-Specific Setup Complexity

For iOS, developers must manually link Firebase SDKs via Cocoapods or SPM, and for JVM, additional initialization is required compared to official SDKs, adding friction to the setup process.

Community-Maintained Risks

As an open-source project maintained by volunteers, updates may be slower, and support less immediate than with official Firebase SDKs, potentially impacting bug fixes and new feature adoption.

Frequently Asked Questions

firebase-kotlin-sdk

What is firebase-kotlin-sdk?

Overview

Use Cases

Best For

Not Ideal For

Pros & Cons

Pros

Cons

Frequently Asked Questions

Related Projects

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firebase-kotlin-sdk

What is firebase-kotlin-sdk?

Overview

Use Cases

Best For

Not Ideal For

Pros & Cons

Pros

Cons

Frequently Asked Questions

Related Projects

Found a gem we're missing?