AI21 Studio is the developer platform of AI21 Labs, which its documentation now calls the AI21 Developer Platform. It gives access to AI21's foundation models (large language models trained on broad data and then adapted to tasks), the Jamba family of open models, which AI21 designs for long-context work such as grounded question answering over long documents and RAG (retrieval-augmented generation, where the model first retrieves relevant text and then answers from it).
In the web console at studio.ai21.com a developer tests prompts in a playground, creates API keys and stores files in a file library. Programs call the models through a public REST API or a Python SDK, and the models are also offered on large cloud platforms. The Jamba models can be fine-tuned, that is, trained further on a company's own examples, with full fine-tuning, LoRA or QLoRA.
The API is billed by usage, per million tokens (pieces of text), after a free trial; a custom plan adds private cloud hosting.