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GPT-5.3-Codex vs Kimi K3

Kimi K3 leads in 2 of 8 categories

Arena ELO

Tie

Cheaper

Kimi K3

Faster

Tie

Detailed Comparison

CategoryGPT-5.3-CodexKimi K3
ProviderOpenAI Moonshot AI
Context Window128K 128K
Input Price ($/1M)$1.75 $0.6 WIN
Output Price ($/1M)$14 $2.5 WIN
Arena ELON/A N/A
CodingN/A N/A
ReasoningN/A N/A
Speed (tokens/sec)N/A N/A
Open SourceNo Yes

Frequently Asked Questions

Which is cheaper, GPT-5.3-Codex or Kimi K3?

Kimi K3 is approximately 80% cheaper than GPT-5.3-Codex per million tokens.

Which has a larger context window?

GPT-5.3-Codex supports 128K context, while Kimi K3 supports 128K.

Is GPT-5.3-Codex or Kimi K3 open source?

GPT-5.3-Codex is proprietary. Kimi K3 is open source.

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