How-to guide: Publisher installation of the ID5 ID for Mobile In-App

  • Posted by Anissa Connor
  • On Jan 25, 2024

If you are a mobile app publisher considering integrating the ID5 ID, keep reading to discover how to deploy our next-generation consented identifier across your inventory to maximize audience addressability and monetization opportunities.

With the growing emphasis on data privacy and deteriorating access to Mobile Ad Identifiers (MAIDs), it’s essential for publishers to utilize effective yet compliant solutions for user identification across various mobile devices and operating systems. 

We know how challenging it can be to navigate through various technologies and adopt new solutions, especially when time is a pressing factor. We are here to offer a helping hand in kickstarting your identity journey with a series of “how-to” guides explaining how publishers can deploy the ID5 ID. While today we’ll be focusing on the mobile in-app implementation, you can take a look at the rest of our guides to learn more about alternative methods of integrating the ID5.

Integrating the ID5 ID

We recommend deploying the ID5 ID in the mobile in-app environment via server-to-server (S2S) integration. This method leverages a specific in-app S2S Fetch Endpoint to retrieve an ID5 ID for a single user. It allows you to reduce page latency and ensures that the ID is readily available at the time of the auction, as it can be delivered with the page content.

To ensure accurate identity reconciliation, we highly advise you to include signals, such as hashed emails, IPs, MAIDs and any other proprietary first-party user IDs, in your request for an ID5 ID. Providing more signals contributes to the integrity of the resulting ID5 ID, strengthening our robust and persistent identifier.

Below, you will find general instructions on how to retrieve an ID5 ID server-side for in-app inventory and make it available in bid requests to your demand partners. All server-to-server requests should be made based on the user and synchronously with them. Before starting, don’t forget to register with ID5 and request your ID5 Partner Number on our website.

Step 1: Check the local storage cache for an available ID5 ID

  • IF there is no cached ID OR if the ID needs to be refreshed OR if the user’s privacy preferences have changed:
    • Initialize a new HTTP POST request to the ID5 endpoint. If you previously had a stored response for a given user on their device, then subsequent requests must include the “signature” as part of the request to ID5;
    • Store the response from ID5 locally, either in-app in local storage or in a database on the server, and provision it to us in future requests for the same user;
  • IF there is a valid, up-to-date value in cache:
    • Pull the latest ID5 ID response from Cache

Step 2: Prepare the data for the bid request using the ID you have from Step 1

  • Include the following fields in the bid request:
    • universal_uid
    • link_type

Step 3: Include this data in each bid request to your demand partners as an eids array.

For more information about setting up your server-side mobile in-app integration, see the detailed ID5 client documentation.

What are the benefits of using the ID5 ID for Mobile In-App?

Still need convincing on why to integrate the ID5 ID? ID5’s next-generation consented identifier has a track record of improving audience addressability for publishers, as well as growing sustainable revenue across all environments without reliance on traditional identifiers.

  • Increased bid density and higher win rates sustaining and fueling media owners’ revenue streams 
  • Advanced data protection and encryption mechanism ensuring that your data is safe and user identity is only shared with authorized partners 
  • Privacy-by-design technology that respects and enforces privacy in the advertising value chain

ID5 is the most adopted ID solution on the market trusted by publishers worldwide. Dive into our insightful collection of case studies to discover how ID5 identity services deliver tangible value for publishers and enable efficient digital advertising while upholding the highest data protection standards

For more information, contact our dedicated publisher team at