OpenCode launches Union Alpha model for free use on OpenRouter

A new AI coding model just appeared on OpenRouter with no price tag, no clear origin story, and capabilities that put it in the same conversation as frontier models. Union Alpha, a collaboration between OpenCode and OpenRouter, went live on September 16 as a “stealth model” designed for coding agents, complete with multimodal support and a context window large enough to swallow entire codebases. The model is free to use during an initial preview period lasting roughly one week. After that, pricing details remain unclear. But for now, developers can experiment with what OpenCode describes as “frontier-level” general-purpose performance without spending a cent. What Union Alpha actually does The headline specs are genuinely impressive for a free offering. Union Alpha supports both text and image inputs, making it useful for tasks where developers need to feed screenshots, diagrams, or UI mockups alongside code. Its 262,144-token context window means it can process roughly 200,000 words of input at once, enough to analyze large repositories or lengthy documentation in a single pass. The model is specifically optimized for agentic coding workflows, the kind of setup where an AI doesn’t...