# Solar Pro 4: AI model fact sheet

- **Provider:** upstage
- **Released:** 2026-08-10
- **Context window:** 524,288 tokens
- **API pricing:** $0.09 / 1M input, $0.36 / 1M output
- **OpenRouter ID:** upstage/solar-pro4
- **Capabilities:** conversation, reasoning, tool-use

Upstage language model for long-horizon agent workflows, office productivity, and document-intensive tasks. Supports text input and output with a 524K context window on OpenRouter.

Source: real side-by-side outputs, pricing and specs at https://rival.tips/models/solar-pro4