Composer

Composer is an AI model that Cursor, the AI coding tool, trained itself. Cursor is best known as a tool that lets you pick from various AI models made by other companies right inside its interface, and Composer is one of those options, except Cursor built it in-house.

Think of it like a delivery service that carries food from famous restaurants but also cooks its own dishes in its own kitchen. Customers can still order from other places, but they can also choose the dish the service made itself.

Composer's existence is also a sign that Cursor isn't just a convenient window into other companies' technology, but a company aiming to build its own computing capacity for training and running models. In fact, one reason Cursor came under the umbrella of the rocket company SpaceX was to secure greater computing resources for training models like this on its own.

Articles describe it with lines like, "the company also trains and ships its own model called Composer." A common misconception is that Cursor is just a wrapper around other companies' models, but Composer shows that isn't the whole picture, since it's a separate model the company built itself.