GPT-5.1-Codex-Max vs Kimi K2 0905
How do these models stack up? Below is an expert side-by-side comparison of specifications, context window capacity, live pricing per million tokens, and standardized benchmark scores for GPT-5.1-Codex-Max and Kimi K2 0905.
GPT-5.1-Codex-Max
GPT-5.1-Codex-Max is OpenAI’s latest agentic coding model, designed for long-running, high-context software development tasks. It is based on an updated version of the 5.1 reasoning stack and trained on agentic...
Kimi K2 0905
Kimi K2 0905 is the September update of [Kimi K2 0711](moonshotai/kimi-k2). It is a large-scale Mixture-of-Experts (MoE) language model developed by Moonshot AI, featuring 1 trillion total parameters with 32...
Technical Specifications
| Specification | GPT-5.1-Codex-Max | Kimi K2 0905 |
|---|---|---|
| Provider | OpenAI | Moonshot AI |
| Context Window | 400,000 tokens | 262,144 tokens |
| Agent Suitability | N/A | N/A |
| Time to First Token (TTFT) | N/A | N/A |
| Deployment Model | managed api | managed api |
| Production Stability | stable | stable |
| API Available | Yes | Yes |
| Released Date | 2025-12-04 | 2025-09-04 |
API Pricing Comparison
Input Price per Million Tokens
GPT-5.1-Codex-Max
$1.25
Kimi K2 0905
$0.60
Output Price per Million Tokens
GPT-5.1-Codex-Max
$10.00
Kimi K2 0905
$2.50
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Benchmark Performance Metrics
Scores show the raw performance percentages verified across key evaluation suites. Higher bars indicate superior accuracy and capability in that domain.
GPT-5.1-Codex-Max Quirks & Gotchas
No developer gotchas reported.
Kimi K2 0905 Quirks & Gotchas
No developer gotchas reported.