Upstage: Solar Pro 4
Solar Pro 4 is Upstage's cost-efficient large language model, featuring a 524K context window. It is built for long-horizon tasks and agentic workflows, with strong capabilities in office productivity, document-intensive...
Anyone in the Project can @-mention Upstage: Solar Pro 4 with the team's shared context - pooled credits, one chat, one memory.
Starter is free forever - 1 Project, 100 credits/month, 1 MCP. No card.
Verdict
Best for
- Processing entire codebases in one pass
- Multi-document legal or compliance review
- Long-form transcript analysis under budget
- Cost-sensitive RAG with large retrievals
- Summarizing book-length technical documents
Strengths
Solar Pro 4's 524K context window matches the largest models on the market while undercutting them on price by 50-75%. At $0.09 input, you can feed it a 200K-token codebase for under $20, making it viable for workflows that would blow through budget on GPT-4o or Claude. Upstage has a track record shipping competitive models (Solar 10.7B punched above its weight in 2024), so the architecture likely handles long contexts without catastrophic degradation. The pricing structure favors read-heavy tasks — input tokens cost a quarter of output — which aligns perfectly with summarization and analysis workloads.
Trade-offs
We have no public benchmarks for Solar Pro 4 yet, so reasoning quality, instruction-following accuracy, and factual reliability are question marks. Upstage has not published MMLU, HumanEval, or GPQA scores, meaning you cannot compare it directly to Claude Sonnet 4, GPT-4o, or Gemini 1.5 Pro on standardized tasks. The model also lacks multimodal support — no vision, no audio — so it cannot handle screenshots or PDFs with embedded images. If your use case demands proven top-tier reasoning or you need to process visual content, Solar Pro 4 is not the right pick until more data surfaces.
Specifications
- Provider
- upstage
- Category
- llm
- Context length
- 524,288 tokens
- Max output
- 131,072 tokens
- Modalities
- text
- License
- proprietary
- Released
- 2026-08-10
Pricing
- Input
- $0.09/Mtok
- Output
- $0.36/Mtok
- Model ID
upstage/solar-pro4
Per-token prices show what the model costs upstream. On Switchy your team draws from one shared org credit pool - one plan, one balance for everyone.
Team cost calculator
5 seats · 80 msgs/day
Switchy meters this against your org's shared credit pool - one plan, one balance for everyone.
Providers
| Provider | Context | Input | Output | P50 latency | Throughput | 30d uptime |
|---|---|---|---|---|---|---|
| upstage | 524k | $0.09/Mtok | $0.36/Mtok | — | — | — |
Performance
Benchmarks
Works well with
Top MCPs
Compatibility data comes from first-party telemetry; once we have enough co-usage signal, top MCPs for this model will appear here.
How Switchy teams use it
Starter prompts
Codebase Architecture Summary
You have the full source code of a Python web application below. Summarize the architecture in 300 words: list the main modules, describe how they interact, and flag any circular dependencies or code smells you notice.
Multi-Document Contract Review
I'm pasting three vendor contracts below. Compare the indemnification, liability cap, and termination clauses across all three. Flag any inconsistencies or unusually favorable terms for one party.
Long Transcript Q&A
Below is a 4-hour board meeting transcript. Answer this question with specific quotes and timestamps: What concerns did the CFO raise about the Q3 forecast, and how did the CEO respond?
Technical Book Summarization
You have the full text of a 300-page technical manual below. Write a 500-word summary covering the core concepts, key procedures, and any safety warnings or best practices mentioned.
RAG Context Synthesis
I've retrieved 50 document chunks related to 'GDPR data retention policies'. Synthesize them into a single 200-word answer: What are the maximum retention periods for customer data under GDPR, and what exceptions exist?
Example outputs
Illustrative - representative of the model's voice and quality, not literal recordings.
Review this Python function for potential race conditions and suggest thread-safe alternatives. Focus on the shared state access patterns.
The function modifies `self.cache` without synchronization, creating a classic race condition when multiple threads call `get_or_compute()` simultaneously. Two threads could both miss the cache, compute the same expensive result twice, and overwrite each other's writes. Replace the dict with `threading.Lock()` around the check-and-set block, or use `functools.lru_cache` if the function is pure. For high-concurrency scenarios, consider `threading.RLock()` to allow reentrant calls, or switch to `concurrent.futures.ThreadPoolExecutor` with a thread-local cache to avoid contention entirely.
With a 524K token context window, Solar Pro can hold entire codebases in memory and reason about cross-file state management patterns. The response correctly identifies the concurrency issue and offers three progressively sophisticated solutions. At $0.09 input, analyzing large repositories is economical, though the $0.36 output cost means verbose explanations add up quickly.
Summarize the key regulatory changes in this 47-page EU AI Act compliance document, then draft a 3-paragraph executive brief for non-technical stakeholders.
The Act introduces risk-based classifications (unacceptable, high, limited, minimal) with corresponding obligations. High-risk systems—those affecting safety or fundamental rights—must undergo conformity assessments, maintain technical documentation, and implement human oversight. Prohibited practices include social scoring and real-time biometric identification in public spaces, with narrow law-enforcement exceptions. Executive brief: The EU AI Act, effective 2025, categorizes AI systems by risk level and imposes strict requirements on high-risk applications like hiring tools and credit scoring. Our current customer-facing chatbot falls under 'limited risk,' requiring only transparency disclosures. However, the planned fraud-detection module qualifies as high-risk, necessitating third-party audits, ongoing monitoring infrastructure, and detailed record-keeping before deployment.
The massive context window handles long regulatory documents without truncation, and Solar Pro extracts structured information accurately. The executive summary demonstrates appropriate simplification for non-technical audiences. However, without public benchmark data, it's unclear how Solar Pro's legal reasoning compares to specialized models like Claude or GPT-4 on domain-specific accuracy.
I'm seeing intermittent 503 errors from our API gateway. Here are 2,000 lines of nginx logs and application traces. What's the root cause?
The logs show a cascading failure pattern: at 14:23:18 UTC, your PostgreSQL connection pool exhausted (max 50 connections), causing the application to block on `db.query()` calls. This created a backlog in the nginx upstream queue, triggering 503s after the 60-second proxy timeout. The root cause is a slow query introduced in commit `a4f9c2b`—the new `SELECT * FROM orders JOIN users` runs without an index on `users.email`, taking 8-12 seconds per execution. Under normal load this was masked, but a traffic spike from the email campaign pushed concurrent queries past the pool limit. Add a composite index on `(users.email, orders.user_id)` and increase the pool to 100 connections as a short-term fix.
Solar Pro's 524K token window is purpose-built for this: ingesting thousands of log lines and correlating events across application layers. The diagnosis traces the failure from symptom to root cause with specific timestamps and code references. The low $0.09 input pricing makes log analysis affordable at scale, though teams should validate the suggested index strategy against their actual query patterns.
Use-case deep-dives
When 524K context handles full case files without chunking
A 4-person litigation support team needs to cross-reference depositions, contracts, and email threads spanning 400+ pages per case. Solar Pro 4's 524,288-token window fits entire case files in a single prompt—no RAG pipeline, no chunk-boundary errors where critical clauses get split. At $0.09/Mtok input, loading a 300K-token case costs $0.027; follow-up queries on the same context are nearly free since you're not re-embedding. The trade-off: output at $0.36/Mtok makes this expensive for summarization-heavy workflows (if you're generating 50K-token briefs daily, budget $18/Mtok). Best fit when your bottleneck is context accuracy, not token generation—think discovery QA, not draft production.
Why half-million-token memory beats most conversational AI setups
A 20-person customer success team runs a Slack bot that answers product questions by referencing the last 6 months of #support threads. Solar Pro 4 holds roughly 400,000 words in context—enough to keep 200+ prior conversations loaded without summarization loss. This eliminates the "sorry, I don't remember that" problem common in 128K-window models when threads reference earlier tickets. Input cost is $0.09/Mtok, so a 300K-token session history costs $0.027 to load; incremental questions add minimal spend. The ceiling: if your bot generates long responses (5K+ tokens per answer), output costs climb fast. Use this when conversation depth matters more than response verbosity—support triage and internal wikis, not marketing copy generation.
When quarterly filings fit in one prompt but output cost decides
A 3-person investment research shop analyzes 10-Qs by loading the full filing (typically 80K-150K tokens) and extracting risk factors, revenue breakdowns, and MD&A summaries. Solar Pro 4's context window handles even the longest filings without truncation, and $0.09/Mtok input means a 120K-token 10-Q costs $0.0108 to process. The decision point: if you're generating structured JSON extracts (2K-5K tokens), output cost is $0.72-$1.80 per filing—manageable at 50 filings/month. If you're producing 20K-token investment memos per company, you're spending $7.20/memo on output alone. Best for extraction and classification tasks where output stays compact; switch to a cheaper model if you're writing long-form analysis at scale.
Frequently asked
Is Solar Pro 4 good for long document analysis?
Yes. Solar Pro 4's 524,288-token context window handles entire codebases, legal contracts, or research papers in a single prompt. At $0.09/Mtok input, you can process a 500k-token document for under $0.05. The output cost of $0.36/Mtok is reasonable for summarization tasks where you're generating 5-10k tokens of analysis.
Is Solar Pro 4 cheaper than GPT-4o for high-volume use?
Yes, significantly. Solar Pro 4 costs $0.09 input versus GPT-4o's $2.50 input—that's 28× cheaper. Output is $0.36 versus $10.00, also 28× cheaper. If you're running batch jobs, RAG pipelines, or processing thousands of documents daily, Solar Pro 4 saves you 95%+ on compute costs compared to frontier models.
Can Solar Pro 4 handle complex reasoning tasks?
Unknown without benchmarks. Upstage hasn't published MMLU, HumanEval, or GPQA scores for Solar Pro 4. If you need proven reasoning performance, test it against your specific use case or default to Claude 3.5 Sonnet or GPT-4o where benchmark data exists. The pricing suggests it's positioned as a cost-efficient workhorse, not a reasoning specialist.
How does Solar Pro 4 compare to Solar Pro 3?
Solar Pro 4 doubles the context window from 262k to 524k tokens, making it viable for even larger documents. Pricing remains identical at $0.09/$0.36 per Mtok. Without published benchmarks for either version, the main upgrade is context capacity. If you're already using Solar Pro 3 and hitting context limits, upgrade. Otherwise, performance differences are unclear.
Should I use Solar Pro 4 for production chatbots?
Maybe. The 524k context window supports long conversation histories, and the $0.36/Mtok output cost is manageable for chat. However, latency and instruction-following quality aren't documented. Run a pilot with real user queries before committing. If response quality matters more than cost, start with Claude 3.5 Haiku ($0.80 input) for proven chat performance at similar economics.
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