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Link to Webstore checkout on Android - US 🇺🇸

To successfully launch Coda Links on Android for users in the United States, developers must comply with Google's External Content Link (ECL) program. Standard hyperlinks are no longer permitted; developers must use Google's designated ECL APIs by the enforcement deadline of January 28, 2026.

Requirement summary

  • Mandatory API Integration: Developers cannot simply put a "naked" hyperlink in the app. They must integrate with Google's External Content Links APIs, through which Google enforces transaction tracking and controls the linkout UX.

  • Controlled User Experience: When a user clicks an external link, this API triggers a system-level information screen (a "warning" or "interstitial") that informs the user they are leaving Google Play and completing a transaction outside the Play billing system. The user must click to confirm in order to proceed.

  • Transaction Reporting: Google indicated that external transactions and downloads may be subject to reporting requirements once service fees are activated. Thus, implementation work related to Transaction Reporting is currently not required in the US.

Refer to this official page for the latest information on Google's requirements & fees: Play Console Help > Enrolling in the external content links program for users in the US

Below is the step-by-step integration guide for linking users to your Coda Webstore, based on Google's ECL requirements:

Prerequisites

Ensure that you have followed the Steps to Launch your Web Store, and published your Coda Webstore.

This is the standard integration that allows users to purchase items on the web store and have the items fulfilled in-game. If you already have this set up with Coda, no further modifications are required.

Step 1: Program Enrollment on Play Console

Before integrating the APIs, you must establish the necessary contractual ties and permissions with Google:

  1. Complete Google’s External Content Links Declaration Form and any required onboarding steps with Google's support team.

  2. In the Google Play Console, navigate to Settings > External content links to officially enroll the app(s) that will use Coda Links.

Next, let's explore the technical details for implementation

Flow Overview

Step 2: Construct the URL & link users out from your Android App

  1. Update Play Billing Dependencies: Add or update the Play Billing Library to version 8.2.1 or higher in your Android app. If migrating from an older version, follow Google's official migration guide first.

  2. Check Availability: Programmatically call isBillingProgramAvailableAsync() to verify the program is available on the device.

  3. Generate a Transaction Token: When the user clicks a link/button that should take them to out-of-app, before redirecting the user, call createBillingProgramReportingDetailsAsync(). This generates a unique externalTransactionToken.

Note: You must generate a new externalTransactionToken every single time a user attempts to visit the external web store (i.e every click)

  1. Construct the checkout URL: Build the destination URL dynamically. It must append your externalTransactionToken alongside the standard Coda parameters. Your final URL should include:

    • mode (e.g., mode=lite tells your webstore that this is a linkout purchase, and to trigger the express checkout flow for maximum conversion-friendliness)

    • sessionToken (for extracting the user's UID/account. The Coda webstore uses this information to validate the checkout with your server, and ensure item delivery is made to the right user.)

    • skuId (the specific item selected, exactly as configured on the Coda webstore)

    • utm parameters (source, medium, campaign)

    • externalTransactionToken (the token generated in Step 3)

For example:

  1. Launch the Link: Pass your constructed URL into the launchExternalLink method, with the externalTransactionToken and set the LaunchMode (which typically opens the URL in an external browser)

User Experience: Google will automatically intercept this call and display a mandatory system-level warning sheet (interstitial) informing the user they are leaving Google Play, which the user must confirm to proceed to checkout.

Step 3: Post-Purchase UX & Deep Linking

  1. Item Fulfillment: When the payment succeeds, Coda Webstore completes the payment and automatically sends a server-to-server item fulfillment request to your backend. This should already be covered in Steps to Launch your Web Store. No change is required here.

  1. User can click to go back to App via deep link: To ensure this redirection happens smoothly, you must provide Coda with a deep link that can redirect users back to your Android app upon a successful purchase.

    • Once the user is deep-linked back to your app, they should seamlessly receive their items. In addition, your app can display a purchase success screen with confetti animations!

    • Refer to Redirecting users from Coda Links back to your appto learn how to setup back-to-app redirection correctly for your Android App.

  2. User can explore Webstore's offers & LiveOps campaigns! If you configure any of the Webstore LiveOps offers in Commerce LiveOps, the post-purchase screen will display them to the user, encouraging them to explore & become a loyal webstore user

seedling

Why having LiveOps features on Coda Links is crucial for your long-term revenue

  • Linkouts are not (actually) free: Including in the US, Google and Apple are fighting tooth and nail to impose fees on external purchases to protect their revenue streams. For instance, Google charges up to a 20% commission on purchases made within 24 hours of a user following an external payment link. Similarly, Apple imposes a 15% commission on website sales initiated within 7 days of an end user tapping an out-of-app link. If users stick exclusively to linkout payments directly from the app, publisher margins will continuously be undercut by these fees with no way out.

  • Webstore loyalty builds long-term profitability: Converting purchasers from in-app to webstore should be the ultimate goal. Publishers can use elements on the linkout success page to convert users into direct webstore customers, which makes the long-term cost per transaction significantly lower. When users build a habit of going directly to out-of-app channels like a webstore, they bypass the in-app link altogether. These direct visits make their future purchases completely out-of-reach for the app platforms, meaning all fee savings go straight to the publisher's bottom line.

Step 4: Report external transactions to Google (not yet required)

exclamation

This is part of the Transaction Reporting requirement. They are not required at the time of writing this article.

These steps are only required when Google activates fees for the External Content Links Program for users in the US

Because developers remain the contracting party for external transactions, Google currently requires an infrastructure for transaction reporting, which will be activated only if/when Google implements service fees.

  1. Receive the Callback: When a user successfully completes a purchase on the Coda checkout page, Coda will send a server-to-server top-up request to your backend. This payload will contain the externalTransactionToken that you originally passed in the URL, along with the payment confirmation data.

  2. Report external transactions to Google (not yet mandatory): Upon receiving the top-up confirmation, your backend must call the Google Play Developer API (externalTransactions endpoint). You have 24 hours to report the transaction by passing both the final sale amount and the externalTransactionToken back to Google.

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