:wave: Hey folks! Has anyone here implemented Goo...

# kobweb

[Kumaran Masilamani]

👋 Hey folks!
Has anyone here implemented Google (or any social) login in Kobweb?
I'm working on adding a "Sign in with Google" button using Firebase Auth on the kobweb frontend, and then passing the token to a Ktor backend for verification.
Would really appreciate any GitHub examples or documentation links 🙏
(Vibe coding isn't cutting it this time 😅)

[Filip Wiesner]

That shouldn't be anything Kobweb specific. You are basically asking, "How does Firebase Auth work in Kotlin/JS?" This tutorial should cover it.

And for BE, you have to use Firebase Admin tools to verify the resulting JWT token

[Kumaran Masilamani]

Thanks for the link! I’ve already looked through similar Kotlin/JS references.
My main question is about how to organize Firebase-related code in a fullstack Kobweb project.
For example, I cloned the fullstack chat example from Kobweb and added

kotlin

implementation(npm("firebase", "11.6.0"))

inside the
jsMain block of site/build.gradle.kts.
But even after that, I’m still unable to access Firebase classes from my Kotlin code.
Any example repo on how this is typically set up would be helpful? (Me being a back-end developer)

[Filip Wiesner]

> I’m still unable to access Firebase classes from my Kotlin code
That's because it's JS library. Not Kotlin library. You have to create your own bindings or use some library with bindings like firebase-kotlin-sdk.
I used to use firebase-kotlin-bindings from @David Herman but I recently migrated to the KMP library.

[Filip Wiesner]

My main question is about how to organize Firebase-related code in a fullstack Kobweb project

Personally, I don't really want to give advice on architecture of your app. I don't have that figured out myself. I just have some sort of FirebaseSource implementation on all platforms and I call that pretty much directly from presentation layer (with one "use-case layer" between).

[Ahmed Riyadh]

There is a JVM library which you can use from the server side to validate the token you get from the frontend:

[versions]
# For latest version: <https://mvnrepository.com/artifact/com.google.api-client/google-api-client>
google-api-client = "2.7.2"

[libraries]
# <https://developers.google.com/api-client-library/java/google-api-java-client/setup#google-api-client>
google-api-client = { module = "com.google.api-client:google-api-client", version.ref = "google-api-client" }

Refer to the official example.

Here is an example usage:

private val googleIdTokenVerifier =
        GoogleIdTokenVerifier.Builder(NetHttpTransport(), GsonFactory())
            .setAudience(
                listOf(
// For multiple apps                   googleAndroidClientId,                    googleIosClientId
                )
            )
            .build()

// Null if the id token is invalid
val idToken: GoogleIdToken? = googleIdTokenVerifier.verify(googleIdToken)

[Filip Wiesner]

OP mentioned they are using Firebase auth so the Firebase-Admin JVM sdk should probably be used on the BE. If they are using JVM on BE...

[Kumaran Masilamani]

Thank you for all the responses. The back-end is fine, and I have the options to validate the token and send a JSON based on the result. My only grey area is the frontend in Kobweb. I am going to try this library-> https://gitliveapp.github.io/firebase-kotlin-sdk/

[David Herman]

Yeah, the gitliveapp library is probably the way to go. Good luck!