# River API Documentation

> River lets you sample from and fine-tune hosted large language models through the Python `river-client`.

## Documentation

- [River API guide](https://docs.river.ai/index.md): Installation, authentication, sampling, supervised fine-tuning, reinforcement learning, loss functions, throughput, and checkpoints.
- [River Python API reference](https://docs.river.ai/python-api.md): Every public class, method, type, and error in the `river-client` package, with signatures and parameters.