Fantasy – Build AI agents with Go. Multi-provider, multi-model, one API (github.com)

Fantasy is a new Go library (preview) that lets developers build AI agents with a single, consistent API across multiple model providers. With a few lines of code you pick a provider (examples include OpenRouter, Azure, Bedrock or any OpenAI-compatible endpoint), choose a model, add custom "tools" (small functions the agent can call), and run the agent — even compile it to native machine code for distribution. The repo includes examples showing provider/model selection, tool creation, agent configuration with system prompts, and a simple agent.Generate call to run queries. This is significant because it abstracts away provider-specific SDK differences, reducing vendor lock‑in and making it easier to swap models/providers in production. The tool system supports custom integrations (e.g., fetching live data), and the API is geared toward building autonomous coding assistants (Fantasy powers the Crush coding agent). Important technical notes: Fantasy is preview quality and may change, supports many providers via dedicated packages or an openaicompat layer, and currently does not support image/audio models, PDF uploads, or provider-managed tools (web_search, etc.). The project is open-source and welcomes issues and PRs to expand provider support and capabilities.