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Stealth: union-alpha:free
union-alpha:free
262.1K context131.1K outToolsVisionStructured
Released Sep 16, 2026Updated Sep 16, 2026
Union Alpha is a multimodal model built for research, coding, and agentic workflows, while delivering frontier-level performance across a broad range of general-purpose tasks. Union Alpha is a stealth model. It is developed and operated by a third-party provider who has chosen to remain anonymous during this preview. OpenRouter routes requests to it and is not its developer, owner, or provider. Prompts and completions may be retained by the provider but are not used for training; all other use is governed by the Stealth Model Terms
Tokenizer OtherExpiration Dec 2098
Pricing
Input price
$0.00/ 1M tokens
Output price
$0.00/ 1M tokens
Context window 262.1K tokensCompatible endpoints openaiVendor Stealth
Uptime
Performance
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Usage & Ranking
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Supported parameters
All providers = every upstream serving this model supports it. Some providers = depends on which upstream handles the request. Default = the value sent when you leave the parameter unset.
| Parameter | Providers | Default |
|---|---|---|
| max_tokens | Some providers | - |
| response_format | Some providers | - |
| temperature | Some providers | - |
| tool_choice | Some providers | - |
| tools | Some providers | - |
| top_p | Some providers | - |