Last modified: Nov 24, 2023

Developing a multi-app solution in Altinn

Considerations and explanations of how to go about when creating a multi-app solution

What is a multi-app solution?

A multi-app solution is a solution consisting of two or more cooperating applications, where typically application A will trigger the creation of a new instance of application B. As a part of the instantiation of application B it is possible to prefill the instance with specific data from the running instance of application A.

This guide takes you through a multi-app solution consisting of two apps; application A and application B, but the concept can be extended to contain several applications of type A or type B, or both types.

Example architecture of a multi app solution


  • An Instance: When talking about instances in an application-context, these are unique pieces of data that describes details about the particular session going on in the application. The data includes information on who is filling in the data and what the data is.
  • Application A: This will be an application that acts as a regular Altinn application which means end-users will interact with it. While filling in the form they will be working on their own private instance. However it will differ from other Altinn apps since the service owner has customized it to include actions that will create a new instance of the application B.
  • Application B: This will be an application that may have multiple purposes, but its main purpose will be to receive and handle data from application A. This application will differ from other Altinn apps since instances are created by triggers in another application.

Do I need a multi-app solution?

Altinn offers a robust set of APIs and event support for processing data from Altinn Apps. However, if these options do not align with your needs, you might consider a multi-app solution.

Use cases where you can consider using a multi-app solution:

We have outlined some common use cases that may warrant the multi-app approach.

  • The organization has limited development capacity or does not want to develop and maintain a new system for processing data from Altinn.
  • Existing setup within the organization for processing data from Altinn does not satisfy requirements for security.

By implementing a multi-app solution, an organization can use the Altinn inbox for their organization to receive data. In most cases the people required to process the data will already have access to the organization in Altinn or can be granted this access. The last application in the data flow (application B in our case), can set authorization rules requiring a specific role before granting access to the data, hence supporting limiting access to sensitive data to people with an official need.

How does the multi-app solution actually work?

A multi-app solution is a way of configuring multiple forms to communicate through API calls. The specific communication we will describe in this guide is the creation of a new instance of an application (B) triggered by another application (A). A typical scenario would be that an end-user fills out or uploads information in an instance of application A. And when pressing the button to submit the form, an API call is sent to another application (B), creating a new instance of this application where the answers from application A is a part of the information.

An integration between the app and Maskinporten might be required

In order for an application to perform actions on another application such as creating a new instance on behalf of and end user or organisation, it needs to be authorized. By nature, the request to create the instance of application B will include the credentials of the end user filling out application A. In most cases this end user will not be authorized to instantiate new instances on behalf of the organisation that owns application B, thus this will fail. A way to ensure the application is authorized to perform the instantiation action, is to use the application owners credentials instead of the end user’s credentials. This is achieved by using a Maskinporten integration to generate a token that represents the organisation and adding this token to the requests that application A makes towards application B.