Language support

The App Engine standard environment currently supports Python, Java, Go, PHP, and Node.js. The runtime for each of these languages includes core features and tools such as development servers, packaging and deployment support, scaling, task queues, and App Engine service integrations. The exact set of supported features varies between languages. For example, Google Cloud Endpoints integrations are currently supported in Java and Python, but not Go or PHP.

Due to the sandboxed nature of the App Engine standard environment, some language features and frameworks are limited. For example, support for concurrency varies between languages. Java 7 has partial support for threads, but threads cannot outlive the request, and threads should be created through the Google App Engine ThreadManager. For applications built in Go, goroutines are executed on a single thread, and cannot execute in parallel. To further complicate this issue, background threading behavior and support varies by type of scaling, with automatic scaling being more restrictive than manual and basic scaling.