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GPT-5 Codex vs Kimi K2.8 Preview

Comparing GPT-5 Codex and Kimi K2.8 Preview across benchmarks, pricing, and capabilities.

OpenAI · Moonshot AI · Updated for 2026

Which is better?

GPT-5 Codex and Kimi K2.8 Preview trade strengths across price, capabilities, and technical limits. The better choice depends on the workload.

Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.

Choose GPT-5 Codex

  • you are already invested in the OpenAI ecosystem

Choose Kimi K2.8 Preview

  • you want the most recent training data — it shipped Sep 2026

At a glance

The differences that matter most.

GPT-5 Codex
OpenAI
Kimi K2.8 Preview
Moonshot AI
Benchmark wins
—
—
Input price
— / M
— / M
Output price
— / M
— / M
Context window
—
1,048,576

Individual benchmarks

1 reported for GPT-5 Codex · 0 for Kimi K2.8 Preview

No common benchmarks found

GPT-5 Codex and Kimi K2.8 Previewdon't have any common benchmark datasets to compare. They may have been evaluated on different testing suites.

Human preference

Blind head-to-head votes and playground preference scores

Context Window

Maximum input and output token capacity

Only Kimi K2.8 Preview specifies input context (1,048,576 tokens).

OpenAI
GPT-5 Codex
Input- tokens
Output- tokens
Moonshot AI
Kimi K2.8 Preview
Input1,048,576 tokens
Output- tokens
Sun Sep 20 2026 • llm-stats.com

Input capabilities

Documented input modalities across available providers

Kimi K2.8 Preview supports multimodal inputs, whereas GPT-5 Codex does not.

Kimi K2.8 Preview can handle both text and other forms of data like images, making it suitable for multimodal applications.

GPT-5 Codex

Text
Images
Audio
Video

Kimi K2.8 Preview

Text
Images
Audio
Video

License

Usage and distribution terms

Both models are licensed under proprietary licenses.

Both models have usage restrictions defined by their respective organizations.

GPT-5 Codex

Proprietary

Closed source

Kimi K2.8 Preview

Proprietary

Closed source

Release Timeline

When each model was launched

GPT-5 Codex was released on 2025-09-15, while Kimi K2.8 Preview was released on 2026-09-11.

Kimi K2.8 Preview is 12 months newer than GPT-5 Codex.

GPT-5 Codex

Sep 15, 2025

1.0 years ago

Kimi K2.8 Preview

Sep 11, 2026

1 weeks ago

12mo newer

Knowledge Cutoff

When training data ends

GPT-5 Codex has a documented knowledge cutoff of 2024-09-30, while Kimi K2.8 Preview's cutoff date is not specified.

We can confirm GPT-5 Codex's training data extends to 2024-09-30, but cannot make a direct comparison without Kimi K2.8 Preview's cutoff date.

GPT-5 Codex

Sep 2024

Kimi K2.8 Preview

—

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Judge for yourself.

Run your own prompts against GPT-5 Codex and Kimi K2.8 Preview side-by-side, then vote on the output you prefer.

GPT-5 Codex
✓ Preferred
Kimi K2.8 Preview
Open in Playground

FAQ

Common questions about GPT-5 Codex vs Kimi K2.8 Preview.

Which is better, GPT-5 Codex or Kimi K2.8 Preview?

GPT-5 Codex (OpenAI) and Kimi K2.8 Preview (Moonshot AI) each have strengths in different areas. Compare their benchmark scores, pricing, context windows, and capabilities above to determine which fits your needs.

How does GPT-5 Codex compare to Kimi K2.8 Preview in benchmarks?

GPT-5 Codex scores SWE-Bench Verified: 74.5%.

What are the context window sizes for GPT-5 Codex and Kimi K2.8 Preview?

GPT-5 Codex supports an unknown number of tokens and Kimi K2.8 Preview supports 1.0M tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between GPT-5 Codex and Kimi K2.8 Preview?

Key differences include multimodal support (no vs yes). See the full comparison above for benchmark-by-benchmark results.

Who makes GPT-5 Codex and Kimi K2.8 Preview?

GPT-5 Codex is developed by OpenAI and Kimi K2.8 Preview is developed by Moonshot AI.

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