Solar Pro 2 (Preview) is a high-performance large language model developed by Upstage, released in May 2025 as the successor to the original Solar Pro architecture. The "Non-reasoning" variant, also known as Chat Mode, is designed for rapid conversational interactions and general-purpose natural language tasks, prioritizing speed and fluency over the structured, multi-step logic found in the model's parallel "Reasoning Mode."
The model is built on a 31-billion parameter architecture, representing a significant scale increase from the 22B parameters of its predecessor. Despite this growth, it is engineered for resource efficiency, utilizing Upstage's proprietary architectural optimizations to deliver performance levels comparable to models more than twice its size. It is particularly noted for its strong performance on multilingual benchmarks, especially in Korean and English.
Key technical features include a 64,000-token context window, which doubled the processing capacity of previous generations. This enables the model to handle larger document sets and maintain coherence in extended dialogue. In its non-reasoning configuration, the model is optimized for lower latency and reduced computational cost, making it suitable for real-time applications such as customer support, summarization, and creative writing.