Solar Pro 4

Upstage's proprietary agentic flagship, built for multi-step work across long documents, terminal tasks, and tool calls. It supports a 512K-token context window, up to 128K output tokens, adjustable reasoning effort, and English, Korean, and Japanese. Upstage says it trained and validated the model with OfficeVerse, a pipeline that synthesizes and grades complete office-work deliverables across 11 industry domains and 12 task types.

Compared with Solar Pro 3, Upstage reports the largest gains on work-like agent evaluations, including +13.8 points on terminal tasks, +11.9 on BrowseComp web research, and +7.4 on GDPval. The model is API-only; its architecture, parameter count, training scale, and base checkpoint have not been disclosed.