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This section provides a detailed walkthrough on how to integrate the Truecaller SDK with the Otpless Headless SDK.

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Step 1: Prerequisites

  1. Before you proceed with integrating Truecaller SDK, make sure to complete the integration steps from the OTPless Android Headless SDK Documentation.
  2. Make sure you have ask OTPless support to enable Truecaller SSO

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Step 2: Add Dependency

Add the required SDK dependencies
Build.gradle
dependencies {
    implementation ("io.github.otpless-tech:otpless-truecaller-sdk-impl:latest_version")
}
Use the latest version of - Otpless Truecaller SDK

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Step 3: Create Truecaller App and Update Client Id

  • Register your app on the Truecaller Developer Console.
  • Copy the below line of code in your string.xml.
  • Replace TRUECALLER_CLIENT_ID with the client id provided by truecaller on dashboard.
<string name="otpless_truecaller_client_id">TRUECALLER_CLIENT_ID</string>
During development, make sure to also register your test phone numbers and SHA-256 fingerprints in the same section to avoid authentication failures.

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Step 4: Create Truecaller request

  • All Parameters are optional and has a equivalent map with the parameters of Truecaller SDK
Kotlin
val trueCallerRequest = OtplessTruecallerRequest(
    heading = OTHeadingConsent.SDK_CONSENT_HEADING_LOG_IN_TO
)

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Parameters

  • footerType → Type of footer (e.g., disclaimer or consent note).
  • shape → Button shape (rectangle, rounded, circular).
  • verifyOption → Verification method (auto/manual/server-side).
  • heading → Heading or consent text above the button.
  • loginPrefixText → Prefix text before the login button (e.g., Login with).
  • ctaText → Call-to-action text inside the button.
  • locale → Language/region setting for UI texts.
  • buttonColor → Background color of the login button.
  • buttonTextColor → Text color of the login button.

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Step 5: Initialize the Truecaller SDK

  • Initialize the Truecaller SDK inside your Activity or Fragment. This step ensures that the SDK is properly set up to handle authentication flows via Truecaller.
  • You should call initTrueCaller after calling OtplessSDK.init in activity or onViewCreated method of fragment.
  • initTrueCaller returns boolean which tells if truecaller authentication is supported or not.
  • If truecaller authentication is not supported then you should continue with smart authentication.
Kotlin
// initialize the truecaller
val initResult = OtplessSDK.initTrueCaller(requireContext(), trueCallerRequest) {
    // provide the scope
    OTScopeRequest.FragmentRequest(fragment, listOf(OTScope.OPEN_ID, OTScope.PHONE, OTScope.PROFILE))
    // OTScopeRequest.ActivityRequest(activity , listOf(OTScope.OPEN_ID, OTScope.PHONE, OTScope.PROFILE))
}
// If initResult is true you can proceed to trigger Truecaller request via OTPless SDK

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Step 6: Handle onActivityResult

Depending on your integration type, override the onActivityResult method in the correct component:
  • Fragment → if you used OTScopeRequest.FragmentRequest
  • Activity → if you used OTScopeRequest.ActivityRequest
Kotlin
override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
    OtplessSDK.onActivityResult(requestCode, resultCode, data)
}

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Step 7: Start the Truecaller SSO Flow

  • To start the sign-in process with Truecaller, create an Otpless request and set the channel type to TRUECALLER.
  • Invoke the SDK using OtplessSDK.start.
Kotlin
if (initResult) {
    lifecycleScope.launch {
        val request = OtplessRequest()
        request.setChannelType(OtplessChannelType.TRUECALLER)
        OtplessSDK.start(request, this::onOtplessResponse)
    }
}

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Truecaller Native Authentication Flow

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