LLM Perks

Solar Pro4

Upstage · All Solar models
Free right now Frontier New
ReasoningTool useLong context

Solar Pro4 is a language model from Upstage. It is currently free at 1 provider with up to 524K tokens of context. The model supports step-by-step reasoning, supports tool calling.

Developer
Upstage
Context
524K tokens
Type
Text
License
Proprietary
Free since
November 7, 2026

Where to use Solar Pro4 for free

Each row is a separate free endpoint with its own limits.

ProviderContextLimitCard
UnoRouter
solar-pro4:free
524K No-card free models use shared capacity and per-model limits; availability can change. No Open

Quick start

curl https://api.unorouter.com/v1/chat/completions \
  -H "Authorization: Bearer $UNOROUTER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "solar-pro4:free",
    "messages": [{"role": "user", "content": "Hello!"}]
  }'

Example for UnoRouter. Any OpenAI-compatible client works: Cursor, Cline, OpenCode, Open WebUI.

Benchmarks

Intelligence Index
28.2
GPQA Diamond
89.1%
Humanity's Last Exam
29.2%
Long context (LCR)
74.0%

Source: Artificial Analysis · Solar Pro 4

Similar free models

FAQ

Is Solar Pro4 free?

Yes. As of November 10, 2026, Solar Pro4 is free at UnoRouter. Each provider has its own limits — see the table above.

What is the context window of Solar Pro4?

The largest context among free routes is 524,300 tokens. Some providers cap it lower.

How do I call Solar Pro4 via API?

Use any OpenAI-compatible client with base URL https://api.unorouter.com/v1, model ID solar-pro4:free, and a UnoRouter key.

How good is Solar Pro4?

Artificial Analysis Intelligence Index: 28.2, GPQA Diamond: 89%. For comparison, the strongest free model in the catalog right now is GLM 5.3 Flash.

Is Solar Pro4 open-weight?

No, it is proprietary: access is only through provider APIs.