How to Run Union Alpha Free for 7 Days

OpenCode has opened a one-week free window on Union Alpha, an experimental stealth model built for autonomous software engineering. If you drive your coding with AI agents, you can point your setup at it right now and pay nothing per token.

Every token is free for the seven-day preview, and your codebase, context, and prompts are not used for model training. Two ways to reach it: inside OpenCode itself, or routed through OpenRouter.

Tutorial

1. Open OpenCode and run Union Alpha directly inside it. The free access window is live there for one week.

1. Or route it through OpenRouter instead. Use the model ID stealth/union-alpha on OpenRouter's standard OpenAI- or Anthropic-compatible endpoints.

1. Point your CLI tool or IDE agent harness at that endpoint. This is what the model was tuned for: complex multi-file refactoring, terminal execution, and recursive tool calling.

1. Feed it screenshots and diagrams when text is not enough. Union Alpha takes images, UI screenshots, and visual architecture diagrams natively alongside raw code.

Wrapping Up

You now have a free week on a model built for agentic coding, reachable from OpenCode or OpenRouter, with no per-token charge and no training on your code. Wire it into your CLI or IDE harness and throw a real bug fix or a heavy repo at it while the preview lasts. After seven days the free tier closes, so use it before then.