Use App Engine instead of customization

  • Release version: Zurich
  • Updated July 31, 2025
  • 4 minutes to read
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    Summary of Use App Engine instead of customization

    ServiceNow encourages customers to use App Engine development tools, like Creator Studio, App Engine Studio, and ServiceNow Studio, to build new applications rather than heavily customizing existing ones on the ServiceNow AI Platform. This approach helps maintain platform integrity and eases future upgrades while supporting your company’s unique business needs.

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    When to Customize vs. When to Use App Engine

    • Customize existing applications only when extending the original purpose of that application (e.g., adding IT functionality to IT Service Management (ITSM)).
    • Create new applications using App Engine when your requirements do not align with the intended workflows of existing applications (e.g., building a travel request process instead of repurposing ITSM workflows).

    Why Avoid Heavy Customization of Existing Applications

    • Workflow conflicts: Combining distinct workflows (like ITSM and a travel request workflow) leads to diverging features, complex troubleshooting, and potential performance degradation.
    • Upgrade challenges: Custom code is excluded from automated platform updates, requiring manual intervention and increasing upgrade time and resources.
    • Support limitations: ServiceNow Customer Support does not troubleshoot issues caused by custom code, placing the responsibility on your team to test and maintain customizations.
    • Technical debt: Over-customizing can complicate future platform upgrades and increase maintenance burden.

    Customization vs. Configuration

    • Customization involves code changes to baseline applications and carries ownership and maintenance responsibilities.
    • Configuration changes product behavior without modifying baseline code and is preferred when adapting applications within their intended scope.

    Practical Recommendations

    • Maximize use of configuration options before considering customization.
    • Customize applications only to extend their original intent.
    • Use App Engine developer products to create new applications for requirements outside the scope of existing apps, ensuring cleaner, maintainable implementations aligned with ServiceNow best practices.

    App Engine development tools, such as Creator Studio, offer an excellent alternative to customizing existing applications on the ServiceNow AI Platform.

    When your company needs to add new functionality to the ServiceNow AI Platform, you can customize existing applications, such as IT Service Management (ITSM), or create a new application using App Engine developer products, such as App Engine Studio, Creator Studio, or ServiceNow Studio. A simple guideline for which path to choose is:
    • If the customization extends the intended purpose of the application, it works better to customize. For example, you can add IT functionality to ITSM.
    • If the customization doesn’t extend the intended purpose of the application, it works better to create a new application using App Engine developer products. For example, do not repurpose the ITSM workflow to add a travel request workflow.

    Examples of when to use App Engine

    ServiceNow products work best when they’re used as they were intended. If you find yourself heavily customizing an application to repurpose it, a better plan is to create a new application using App Engine developer products.

    The following scenarios demonstrate where creating a new application works better than heavily customizing an existing ServiceNow application:
    • Your company has a business process that augments existing product functionality but doesn’t follow the same workflow exactly.
    • You have a novel use case for an app that doesn’t align with any product workflow.
    • You have a use case that could be built by heavily customizing an out-of-the-box application, but it doesn’t align with what the existing application was intended to do.

    Let’s dive deeper into the last use case.

    Issues with repurposing existing products

    ServiceNow applications come with roles, processes, and flows that are specially tailored to their use case. For example, ITSM apps help with IT users, IT issues, IT reports, and IT cases.

    You might have an idea for an app that’s similar to but doesn't exactly align with ITSM. Because ITSM gives you a starting point, you might be tempted to customize ITSM to add the new functionality. For example, ITSM tracks IT issues, and a travel app you want to create might track travel requests. While the workflows sound similar, in fact, they use very different data, different user interfaces, and the details of each workflow vary greatly. Rather than heavily customize ITSM to repurpose it, a better plan is to use App Engine developer products for the following reasons:
    • Combining two workflows creates conflicts.
    • Customizing applications has implications.

    Combining two workflows creates conflicts

    In the ITSM example, the repurposing of ITSM to include a travel workflow uses different data, different tables, different roles, and different workflows than ITSM. As ITSM, ITSM customizations, and the travel workflow grow over time:
    • Their features will continue to diverge.
    • Adding new functionality or fixing problems in one workflow might adversely impact the other.
    • The performance of ITSM may suffer.
    • The code base will grow and the two purposes of ITSM will make troubleshooting more difficult.
    • Quality engineers will require two different testing frameworks.

    All these issues may cause unnecessary complications, poorer performance, upgrade delays, and software problems.

    Customizing applications has implications

    The ServiceNow AI Platform is built to embrace customization and configuration. The ServiceNow AI Platform is flexible enough to fit your company’s business needs. How you customize ServiceNow applications, however, can have significant impacts on ServiceNow support, upgrading to future ServiceNow AI Platform versions, and the functionality of the platform.

    Let’s start by differentiating customization and configuration:
    • Customization is any change made to the code that is part of the baseline installation of a ServiceNow instance. You use code to customize applications.
    • Configuration is any change you make to the behavior of a product that does not touch the code in the baseline installation of a ServiceNow instance. You can use system properties, ServiceNow products, or code to configure an application.
    The following are some of the implications that result from customizing applications:
    • If you add code to an application, you own it whether or not it modifies the code in the baseline installation on a ServiceNow instance.
    • The platform marks all customizations and skips them when you update to a new version of the platform. That means you are responsible for manually updating the customizations. This can have a significant impact on the time and resources required to update to new platform versions.
    • The ServiceNow AI Platform uses a framework that supports applications in how they process tasks, how forms are rendered in multiple browsers, and the overall user experience. Introducing customizations can have unintended consequences on this framework.
    • You own the burden of testing custom code and determining if it impacts platform functionality.
    • ServiceNow Customer Support cannot troubleshoot custom code or issues caused by custom code.

    Customization is one of the key features of the ServiceNow AI Platform. However, over-customizing an application to repurpose it is likely to generate technical debt, lengthen your upgrade cycle, and complicate future platform upgrades because the custom code may not easily migrate to new platform versions.

    Conclusion

    Customization and configuration are hallmarks of the ServiceNow AI Platform that enable your company to customize workflows to fit its specific needs. Proceed with these tasks in the following order:
    1. Configure ServiceNow applications as much as you can before customizing them.
    2. Customize an application only when it extends the intent of the application.
    3. Use App Engine developer products, such as App Engine Studio, Creator Studio, and ServiceNow Studio, to create new applications rather than customizing an application to create functionality that doesn’t align with its original purpose.