# Creating a Shared Data Service

A shared data service keeps its state in a private signal, shows it to components read-only with asReadonly() and computed values, and changes it only through its own methods. Every component that injects it sees the same, up-to-date data.

![Cheat sheet: Creating a Shared Data Service](https://fsdtrainingmedia.blob.core.windows.net/public/images/2026/11/8e845f4f69a14b0083b767d58223db69.webp)

- Category: Angular
- Level: Journeyman
- Tags: angular, asReadonly(), Service (angular)
- Updated: November 3, 2026

Source: https://www.ask-codey.com/cheat-sheets/angular-services-creating-a-shared-data-service-cheat-sheet