For the second time in recent months, Amazon and Microsoft are teaming up in artificial intelligence, with Google on the sidelines for now.

On Thursday the two companies rolled out new tools that will make it easier for developers to use open-source artificial intelligence software. This follows the companies' move in August to let its virtual assistants Alexa and Cortana talk with each other as needed.

Getting into the technical weeds, developers can use Gluon, a Python-based application programming interface, to more easily work with MXNet, the AI framework backed by public cloud market leader Amazon Web Services. And in the near future Gluon will make it easier for developers to use the Cognitive Toolkit, the framework that Microsoft open-sourced in 2015. The two companies are publishing the specifications for Gluon so that other frameworks can adopt it, too.

Google is the elephant in the room here. Google open-sourced the TensorFlow AI framework in 2015, and it has since become very popular among researchers -- considerably more popular than the Cognitive Toolkit and MXNet:

https://twitter.com/fchollet/status/915366704401719296

Notably, Google is not among the companies promoting Gluon at this point. (Google declined to comment.) People who wish to use TensorFlow might find it easier to do that with a Google-backed Python API called Keras.

The announcement comes a few months after Apple introduced the Core ML software that's meant to help developers incorporate AI into iOS apps. Apple also released tools for converting models based on other frameworks into its Core ML format.

"We believe it is important for the industry to work together and pool resources to build technology that benefits the broader community," Eric Boyd, corporate vice president of Microsoft's AI and Research group, is quoted as saying in a statement. "This is why Microsoft has collaborated with AWS to create the Gluon interface and enable an open AI ecosystem where developers have freedom of choice."