Google Cloud Platform (GCP) App Engine offers a flexible and serverless platform for developing and deploying web applications and APIs. App Engine pricing is based on several factors, including the runtime environment, instance class, and the amount of resources used. Here are the key components that determine the pricing for GCP App Engine:

1. Runtime Environment:

   • Standard Environment: This environment is designed for building and deploying applications that are stateless and use predefined runtimes, such as Python, Java, Node.js, and more. Standard Environment pricing is based on the number of instance hours used.
   • Flexible Environment: The flexible environment allows you to use custom runtimes and libraries. Pricing is based on vCPU and memory usage.

2. Instance Class:

   • For the Standard Environment, the instance class (F1, F2, F4, etc.) and the number of instance hours determine the cost.
   • In the Flexible Environment, pricing is based on the number of vCPUs and memory allocated to your instances.

3. Auto Scaling:

   • Both standard and flexible environments support auto scaling. You are billed for the number of instance hours used as instances automatically scale up or down based on traffic.

4. Storage and Datastore:

   • Storage and database usage, such as Google Cloud Storage and Google Cloud Datastore, are billed separately based on usage. These costs are not included in the App Engine pricing.

5. Data Transfer:

   • Data transfer costs apply when data is transferred between your App Engine application and other Google Cloud services, external networks, or the internet.

6. Networking:

   • Networking costs may apply for features like load balancing, SSL certificates, and IP addresses.

7. Services and Features:

   • Additional services and features you use in your App Engine applications, such as Task Queues, Memcache, and Search, have their own pricing.

8. Free Tier:

   • App Engine offers a free tier with certain limitations that allow you to run applications at no cost up to specific usage thresholds.