Rig

Rig is an open source Rust library for building applications and agents powered by large language models. It provides one unified API across more than 20 model providers, so a project can switch providers without rewriting its application logic, along with type safe tools and structured output so model responses map onto Rust types. The library is intended for Rust developers who want production oriented performance in agent and retrieval workloads. The site also lists support for more than 10 vector stores, which covers the retrieval side of building LLM applications. Rig is added to a project with the cargo add rig command and is distributed as a standard Rust crate, with its source hosted on GitHub. Rig is released under the MIT license and has no published pricing, since it is a library installed and run within the developer's own application. Costs of calling a model provider's API are separate and set by that provider.