Overview
Solar Mini 4 is Upstage's compact, cost-efficient language model, a 35B-parameter mixture-of-experts with 3B active parameters and a 524K context window. It is built for agentic use cases where response...
Our take
For developers building agentic systems that require a large working memory, Solar Mini 4 offers a competitive option. Its 524,288-token context window is a notable feature for tasks demanding extensive information recall or multi-step reasoning, such as summarising lengthy research papers or processing complex legal documents. Unlike many general-purpose chatbots such as Claude or ChatGPT, which often prioritise conversational fluency, this model explicitly focuses on structured outputs and tool/function calling, making it suitable for programmatic integration rather than direct user interaction. The inclusion of a built-in reasoning mode further supports its application in solving more intricate problems. With an API price of $0.05 per 1 million input tokens, it positions itself as a cost-efficient choice for those with high-volume processing needs, though the absence of a free tier means initial experimentation will incur charges. It is ideal for developers and enterprises who need a compact, cost-effective language model primarily for automated workflows and structured data processing. Those requiring multimodal capabilities or a free entry point should look elsewhere.
How Upstage: Solar Mini 4 stacks up
Among the 15 chatbots & llms tools in our directory, it ranks #10 of 15 on quality (8.2/10), 3% below the 15-tool average of 8.5, and its $0.05/1M input-token rate is in the budget end — 97% cheaper than the 10-model average of $1.99/1M.
Weighing quality against cost, Upstage: Solar Mini 4's cost-per-quality-point of $0.01 places it in the top 20% for value among chatbots & llms tools.
Upstage: Solar Mini 4 in depth
Upstage: Solar Mini 4, built by Upstage, sits in the chatbots & llms space and is a paid tool starting at $0.05/1M tokens. Our editors rate it 8.2 out of 10 based on capability, ecosystem and value. It handles a context window of 524,288 tokens.
On the feature side, Upstage: Solar Mini 4 brings 524,288-token context window, reasoning / chain-of-thought, tool / function calling and structured (json) outputs. These are the capabilities that most shape day-to-day use and separate it from thinner alternatives.
Its biggest strength is low api price — $0.05 per 1m input tokens, cheaper than roughly 75% of comparable models, while the main trade-off to weigh is that no free tier — usage is billed per token. Keep both in mind when deciding whether it fits your workflow.
Upstage: Solar Mini 4 is most often chosen for research and writing. If that matches your goals, it's a strong candidate to shortlist.
Key features
- ✓524,288-token context window
- ✓Reasoning / chain-of-thought
- ✓Tool / function calling
- ✓Structured (JSON) outputs
Pricing
Pros
- +Low API price — $0.05 per 1M input tokens, cheaper than roughly 75% of comparable models
- +Built-in reasoning (chain-of-thought) mode for harder problems
- +Supports tool / function calling for agent-style workflows
- +Can return structured JSON output for reliable parsing
Cons
- −No free tier — usage is billed per token
- −Text-only: does not accept image input
Who should use Upstage: Solar Mini 4
- →Anyone looking for a chatbots & llms tool from Upstage.
- →Teams and individuals focused on research and writing.
- →People who value low api price — $0.05 per 1m input tokens, cheaper than roughly 75% of comparable models.
- →Workflows that need a 524,288 tokens context window.
Who should look elsewhere
- →Anyone who needs a free tier — this tool is paid only.
- →Those for whom no free tier — usage is billed per token is a dealbreaker.
- →Users who can't accept that text-only: does not accept image input.
Best for
10 Best Upstage: Solar Mini 4 Alternatives in 2026
Upstage: Solar Mini 4 is a strong chatbots & llms tool, but it is not the only option. Whether you are after a lower price, different features or a better fit for your workflow, here are the 10 best alternatives to Upstage: Solar Mini 4, ranked and compared.
Anthropic
Claude is Anthropic's family of AI assistants, known for long-context reasoning, careful writing and strong coding…
OpenAI
ChatGPT is OpenAI's flagship conversational AI, powering hundreds of millions of weekly users across web, mobile and…
Google DeepMind
Gemini is Google's natively multimodal model family, deeply integrated across Search, Workspace, Android and the Pixel…
DeepSeek
DeepSeek is a Chinese AI lab that stunned the industry with frontier-level reasoning models at a fraction of typical…
Perplexity AI
Perplexity is an AI answer engine that combines live web search with large language models to deliver cited, up-to-date…
Alibaba Cloud
Qwen is Alibaba's series of open-weight models spanning chat, coding, vision and math.
Mistral AI
Mistral AI is a European lab offering both open-weight and commercial models that punch well above their size.
xAI
Grok is xAI's assistant, tightly integrated with the X platform and trained with a distinctively candid, witty persona.
Meta
Llama is Meta's family of open-weight large language models that became the de-facto foundation for the open-source AI…
Cohere
Cohere's Command models are purpose-built for enterprise retrieval-augmented generation and agentic workflows.
Upstage: Solar Mini 4 vs top alternatives
A side-by-side look at how Upstage: Solar Mini 4 stacks up against its closest rivals.
| Feature | Upstage: Solar Mini 4Upstage | ClaudeAnthropic | ChatGPTOpenAI | GeminiGoogle DeepMind |
|---|---|---|---|---|
| Quality score | 8.2 / 10 | 9.6 / 10 | 9.5 / 10 | 9.2 / 10 |
| Starting price | $0.05/1M tokens | $20/mo | $20/mo | $20/mo |
| Free tier | No | Yes — Free tier available | Yes — Free tier available | Yes — Free tier available |
| API input price | $0.05 / 1M tokens | $8 / 1M tokens | $1 / 1M tokens | $1.5 / 1M tokens |
| API output price | $0.2 / 1M tokens | $40 / 1M tokens | $5 / 1M tokens | $7.5 / 1M tokens |
| Speed | — | Fast | Fast | Fast |
| Context window | 524,288 tokens | 200K tokens | 128K tokens | 1M-2M tokens |
| Categories | Chatbots & LLMs | Chatbots & LLMs, Coding, Writing | Chatbots & LLMs, Coding, Writing | Chatbots & LLMs, Coding, Writing |
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Frequently asked questions
Q. Is Upstage: Solar Mini 4 free?
No — Upstage: Solar Mini 4 is a paid tool, starting at $0.05/1M tokens.
Q. How much does Upstage: Solar Mini 4 cost?
Upstage: Solar Mini 4 starts at $0.05/1M tokens. API usage is around $0.05 per 1M input tokens and $0.2 per 1M output tokens.
Q. What is Upstage: Solar Mini 4 best for?
Upstage: Solar Mini 4 is best suited to research and writing, within the chatbots & llms category.
Q. What are the best Upstage: Solar Mini 4 alternatives?
Popular alternatives to Upstage: Solar Mini 4 include Claude, ChatGPT, Gemini and DeepSeek. Each trades off price, quality and ecosystem differently.
Q. Is there a free alternative to Upstage: Solar Mini 4?
Yes. Claude, ChatGPT, Gemini offer a free tier, making them good starting points if you want to avoid an upfront subscription.
Q. Why switch from Upstage: Solar Mini 4?
Common reasons include pricing, specific feature gaps (No free tier — usage is billed per token; Text-only: does not accept image input), data-privacy requirements, or simply wanting a tool that fits your stack better.
How we rate AI tools
Our quality score weighs capability on real tasks, breadth of features and integrations, pricing and value, and how actively the tool is maintained. Scores are editorial guidance, not benchmarks — always trial a tool on your own workflow before committing. Pricing and features change frequently, so verify current details on the official site.
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