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Solar Pro 4

Upstage· released 10 Aug 2026

upstage/solar-pro4
Input / 1M tokens
$0.09
Output / 1M tokens
$0.36
Context window524K tokens

Longest answer: 131K tokens

reads texttool callingreasoning
See it on openrouter.ai

About

Solar Pro 4 is Upstage’s text model for long-horizon tasks and agentic workflows, with a 524,288-token context window. Its stated areas of strength include office productivity and work involving large volumes of documents. It accepts text and returns text, and supports reasoning and tools. The maximum output is 131,072 tokens. Input costs $0.09 USD per 1M tokens and output costs $0.36 USD per 1M tokens. The model is identified as upstage/solar-pro4, belongs to the upstage family, and was released on 2026-08-10. Those details make context size, tool support and per-token pricing central considerations for teams assessing it for text-based workflows. Its listed capabilities point to tasks where substantial context and multi-step work matter; the facts do not specify support for image, audio or video input.

Who it is for

Teams handling document-heavy work or long-running agent workflows may find its large context window and tool support relevant. It is suited to text input and output.

What is good

  • 524,288-token context window
  • Tools supported
  • Reasoning supported
  • Input costs $0.09 USD per 1M tokens

What to know first

  • Text is the only listed input modality
  • Output costs $0.36 USD per 1M tokens

Verdict

Solar Pro 4 pairs a large context window with tool and reasoning support for text workflows. Its listed prices are $0.09 USD per 1M input tokens and $0.36 USD per 1M output tokens.

Details

Lab
Upstageopenrouter.ai · 3 Oct 2026
Context
524Kopenrouter.ai · 3 Oct 2026
Input price
$0.09 / 1Mopenrouter.ai · 3 Oct 2026
Output price
$0.36 / 1Mopenrouter.ai · 3 Oct 2026
Max output
131,072 tokensopenrouter.ai · 3 Oct 2026
Inputs
textopenrouter.ai · 3 Oct 2026
Open weights
Noopenrouter.ai · 3 Oct 2026

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