Upstage, the South Korean maker of the Solar language models

Background and locations

Upstage was founded in South Korea in 2020. It is headquartered in Seoul’s Gangnam district and also has offices in San Francisco and Tokyo. The company is led by CEO Sunghun Kim. In its own words, its mission is to “build intelligence for the future of work,” and its customers are mostly companies in regulated industries such as insurance, healthcare and financial services.

The Solar model families

Solar is the name of Upstage’s large language models. As of October 22, 2026, two commercial models lead the lineup:

• Solar Pro 4, billed as an “agentic” model for multi-step work: tool calling, terminal tasks and reasoning over long documents;
• Solar Mini 4, a compact model that activates only a small share of its parameters, built to run agents at scale at a controlled cost.

Alongside them, the Solar Open line covers open-weight models published on Hugging Face, including Solar Open 100B and Solar Open2 250B, under an in-house license derived from Apache 2.0. Upstage also offers Syn Pro, a locally trained model optimized for Japan. The company had already released earlier open models such as SOLAR 10.7B.

Document AI, the other specialty

What sets Upstage apart is the link between language models and document understanding. Its Document Parse and Information Extract products turn PDFs, scans and emails into usable data, a key step in building a reliable retrieval-augmented generation system. In practice, many companies struggle less with the model than with the quality of the documents they feed it, and that is the gap Upstage fills.

How to access the models

• The Upstage console and its OpenAI-compatible API, documented at console.upstage.ai.
• The AWS, Azure and Snowflake marketplaces.
• Hugging Face for the Solar Open models.
• Upstage Studio for deploying AI agents in the enterprise.

To see how Solar stacks up against models from other labs, use our model comparison tool or browse the list of AI labs.