Solar Pro 4

Solar Pro 4 is Upstage's flagship model, specialized for agentic use. It is the latest release in the solar-pro line, succeeding solar-pro3. It has a context window of 524288 tokens and a maximum output of 131072 tokens. It accepts and returns text. It supports reasoning mode and tool calling. The weights are not open. Pricing starts at $0.03 per million input tokens and $0.12 per million output tokens, with cached input at $0.006 per million tokens.

Against solar-pro3: window 131K to 524K, input $0.15 to $0.03, output $0.25 to $0.12.

Range across the hosts that serve it: up to $0.30 per 1M input tokens.

• ·524288-token context window
• ·131072-token max output
• ·Reasoning mode supported
• ·Tool calling supported
• ·Text-to-text processing

• Reach for it for agentic workflows with tool use
• Reach for it for long-context document analysis
• Reach for it for generating extended responses
• Reach for it for reasoning-intensive tasks

5 hosts serve this model at the price above · the maker's documentation

The registry keeps the six most recent versions of a line. Older ones stay in the file and can be surfaced without a rebuild.

What is the context window size?

The context window is 524288 tokens.

Does it support tool calling?

Yes, it supports tool calling and reasoning mode.

Is the model open source?

No, the weights are not open.