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KimivsGPT-o3

Moonshot AI vs OpenAI — Side-by-side model comparison

GPT-o3 leads 3/5 categories

Head-to-Head Comparison

MetricKimiGPT-o3
Provider
Arena Rank
#2
Context Window
2M
200K
Input Pricing
Undisclosed/1M tokens
$2.00/1M tokens
Output Pricing
Undisclosed/1M tokens
$8.00/1M tokens
Parameters
Undisclosed
Undisclosed
Open Source
No
No
Best For
Ultra-long documents, research, analysis
Advanced reasoning, agentic tasks, research
Release Date
Mar 18, 2024
Apr 16, 2025

Kimi

Kimi is Moonshot AI's flagship model featuring an industry-leading 2 million token context window, the largest publicly available at launch. This extraordinary context length enables processing of entire books, research paper collections, and massive codebases in a single prompt. Developed by a team of former Google and Microsoft researchers in Beijing, Kimi has become one of China's most popular AI assistants, particularly valued for its ability to analyze very long documents.

View Moonshot AI profile →

GPT-o3

GPT-o3 is OpenAI's most advanced reasoning model, succeeding o1 as the frontier of deliberative AI. It uses an enhanced chain-of-thought approach where the model spends more compute time 'thinking' before responding, dramatically improving performance on complex STEM, mathematical, and logical reasoning tasks. With a 200K token context window and the ability to use tools during reasoning, o3 represents a significant leap in AI problem-solving capabilities. It achieved state-of-the-art results on the ARC-AGI benchmark, demonstrating near-human performance on novel reasoning challenges. The model is particularly strong at multi-step mathematical proofs, complex code debugging, and scientific analysis where careful step-by-step reasoning is essential. Originally priced at a premium, an 80% price reduction in June 2025 made o3 accessible to a much broader range of developers and applications.

View OpenAI profile →

Key Differences: Kimi vs GPT-o3

1

Kimi supports a larger context window (2M), allowing it to process longer documents in a single request.

K

When to use Kimi

  • +You need to process long documents (2M context)
  • +Your use case involves ultra-long documents, research, analysis
View full Kimi specs →
G

When to use GPT-o3

  • +Your use case involves advanced reasoning, agentic tasks, research
View full GPT-o3 specs →

The Verdict

GPT-o3 wins our head-to-head comparison with 3 out of 5 category wins. It's the stronger choice for advanced reasoning, agentic tasks, research, though Kimi holds an edge in ultra-long documents, research, analysis.

Last compared: March 2026 · Data sourced from public benchmarks and official pricing pages

Frequently Asked Questions

Which is better, Kimi or GPT-o3?
In our head-to-head comparison, GPT-o3 leads in 3 out of 5 categories (arena rank, context window, input pricing, output pricing, and parameters). GPT-o3 excels at advanced reasoning, agentic tasks, research, while Kimi is better suited for ultra-long documents, research, analysis. The best choice depends on your specific requirements, budget, and use case.
How does Kimi pricing compare to GPT-o3?
Kimi charges Undisclosed per 1M input tokens and Undisclosed per 1M output tokens. GPT-o3 charges $2.00 per 1M input tokens and $8.00 per 1M output tokens. For high-volume production workloads, the pricing difference can significantly impact total cost of ownership.
What is the context window difference between Kimi and GPT-o3?
Kimi supports a 2M token context window, while GPT-o3 supports 200K tokens. Kimi can process longer documents, codebases, and conversations in a single request. Context window size matters most for tasks involving long documents, large codebases, or extended conversations.
Can I use Kimi or GPT-o3 for free?
Kimi is a paid API model starting at Undisclosed per 1M input tokens. GPT-o3 is a paid API model starting at $2.00 per 1M input tokens.
Which model has better benchmarks, Kimi or GPT-o3?
Kimi's arena rank is not yet available, while GPT-o3 holds rank #2. Note that benchmarks don't capture every use case — we recommend testing both models on your specific tasks.
Is Kimi or GPT-o3 better for coding?
Kimi's primary strength is ultra-long documents, research, analysis. GPT-o3's primary strength is advanced reasoning, agentic tasks, research. For coding specifically, arena rank and code-specific benchmarks are the best indicators of performance.