Yi-1.5 34BvsClaude Opus 4
01.AI vs Anthropic — Side-by-side model comparison
Head-to-Head Comparison
| Metric | Yi-1.5 34B | Claude Opus 4 |
|---|---|---|
| Provider | ||
| Arena Rank | — | #1 |
| Context Window | 4K | 200K |
| Input Pricing | Free (open)/1M tokens | $5.00/1M tokens |
| Output Pricing | Free (open)/1M tokens | $25.00/1M tokens |
| Parameters | 34B | Undisclosed |
| Open Source | Yes | No |
| Best For | Bilingual tasks, fine-tuning, research | Complex reasoning, coding, agentic tasks |
| Release Date | May 13, 2024 | May 22, 2025 |
Yi-1.5 34B
Yi-1.5 34B is 01.AI's open-source model that delivers impressive performance for its size, particularly on bilingual Chinese-English tasks. At 34 billion parameters, it offers a strong foundation for fine-tuning and custom deployments. The Yi series has been influential in demonstrating that high-quality training data and methods can produce competitive models without requiring the largest compute budgets.
View 01.AI profile →Claude Opus 4
Claude Opus 4 is Anthropic's most powerful AI model, holding the #1 position on the Chatbot Arena leaderboard. It represents a breakthrough in extended thinking and agentic capabilities, able to work autonomously on complex multi-step tasks for hours. With a 200K token context window, it excels at analyzing entire codebases, lengthy legal documents, and research papers in a single pass. The model demonstrates exceptional performance in coding (setting new benchmarks on SWE-bench), advanced reasoning, and nuanced writing tasks. Its agentic capabilities allow it to use tools, navigate computers, and execute multi-step workflows with minimal human oversight. Opus 4 is the preferred choice for enterprises requiring the highest quality output on mission-critical tasks where accuracy and depth matter more than speed or cost.
View Anthropic profile →Key Differences: Yi-1.5 34B vs Claude Opus 4
Claude Opus 4 supports a larger context window (200K), allowing it to process longer documents in a single request.
Yi-1.5 34B is open-source (free to self-host and fine-tune) while Claude Opus 4 is proprietary (API-only access).
When to use Yi-1.5 34B
- +You need to self-host or fine-tune the model
- +Your use case involves bilingual tasks, fine-tuning, research
When to use Claude Opus 4
- +You need to process long documents (200K context)
- +You prefer a managed API without infrastructure overhead
- +Your use case involves complex reasoning, coding, agentic tasks
The Verdict
Claude Opus 4 wins our head-to-head comparison with 4 out of 5 category wins. It's the stronger choice for complex reasoning, coding, agentic tasks, though Yi-1.5 34B holds an edge in bilingual tasks, fine-tuning, research.
Last compared: March 2026 · Data sourced from public benchmarks and official pricing pages