The REGION_ID is an abbreviated code that Google assigns
based on the region you select when you create your app. The code does not
correspond to a country or province, even though some region IDs may appear
similar to commonly used country and province codes. For apps created after
February 2020, REGION_ID.r is included in
App Engine URLs. For existing apps created before this date, the
region ID is optional in the URL.
Learn more about region IDs.
Security is a core feature of the Google Cloud, but there are still steps you should take to protect your App Engine app and identify vulnerabilities.
Use the following features to ensure that your App Engine app is secure. To learn more about the Google Security Model and the available steps that you can take to secure your Google Cloud projects, see Google Cloud Platform Security.
Use HTTPS requests to access to your App Engine app securely. Depending on how your app is configured, you have the following options:
appspot.com domainshttps URL prefix to send HTTPS request to the default
service of your Google Cloud project, for example:https://PROJECT_ID.REGION_ID.r.appspot.comTo target specific resources in your App Engine app, use the
-dot- syntax to separate each resource you want to target, for
example:
https://VERSION-dot-SERVICE-dot-PROJECT_ID.REGION_ID.r.appspot.com
To convert an HTTP URL to an HTTPS URL, replace the periods
between each resource with -dot-, for example:
http://SERVICE_ID.PROJECT_ID.REGION_ID.r.appspot.com
https://SERVICE_ID-dot-PROJECT_ID.REGION_ID.r.appspot.com
For more information about HTTPS URLs and targeting resources, see How Requests are Routed.
To send HTTPS requests with your custom domain, you can use the managed SSL certificates that are provisioned by App Engine. For more information, see Securing Custom Domains with SSL.
In each Google Cloud project, set up access control to determine who can access the services within the project, including App Engine. You can assign different roles to different accounts to ensure each account has only the permissions it needs to support your app. For details see, Setting Up Access Control.
The App Engine firewall enables you to control access to your App Engine app through a set of rules that can either allow or deny requests from the specified ranges of IP addresses. You are not billed for traffic or bandwidth that is blocked by the firewall. Create a firewall to:
For details about creating rules and configuring your firewall, see Controlling App Access with Firewalls.
You can use Ingress controls to restrict inbound traffic to your App Engine app. By default, your App Engine app accepts traffic from all network origins. To modify the default settings, and edit and view the available settings, see Specify ingress settings.
The Google Cloud Web Security Scanner discovers vulnerabilities by crawling your App Engine app, following all that links within the scope of your starting URLs, and attempting to exercise as many user inputs and event handlers as possible.
In order to use the security scanner, you must be an owner of the Google Cloud project. For more information on assigning roles, see Setting Up Access Control.
You can run security scans from the Google Cloud console to identify security vulnerabilities in your App Engine app. For details about running the Security Scanner, see the Using Web Security Scanner.
Not supported in the App Engine flexible environment.
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Last updated 2026-06-11 UTC.