GPT-5.1 Codex Max vs Kimi K2.7-Code HighSpeed
GPT-5.1 Codex Max (2025) and Kimi K2.7-Code HighSpeed (2026) are agentic coding models from OpenAI and Moonshot AI. GPT-5.1 Codex Max ships a not-yet-sourced context window, while Kimi K2.7-Code HighSpeed ships a 262k-token context window. On pricing, GPT-5.1 Codex Max costs $1.25/1M input tokens versus $1.90/1M for the alternative. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.
GPT-5.1 Codex Max is ~52% cheaper at $1.25/1M; pay for Kimi K2.7-Code HighSpeed only for coding workflow support.
Decision scorecard
Local evidence first| Signal | GPT-5.1 Codex Max | Kimi K2.7-Code HighSpeed |
|---|---|---|
| Best for | custom coding agents, code generation, and tool loops | custom coding agents, code generation, and tool loops |
| Decision fit | Coding, Agents, and Vision | Coding, RAG, and Agents |
| Context window | — | 262k |
| Cheapest output | $10/1M tokens | $8/1M tokens |
| Provider routes | 1 tracked | 1 tracked |
| Shared benchmarks | 0 shared | 0 shared |
Decision tradeoffs
- Local decision data tags GPT-5.1 Codex Max for Coding, Agents, and Vision.
- Kimi K2.7-Code HighSpeed has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Kimi K2.7-Code HighSpeed has the lower cheapest tracked output price at $8/1M tokens.
- Local decision data tags Kimi K2.7-Code HighSpeed for Coding, RAG, and Agents.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
GPT-5.1 Codex Max
$3,500
Cheapest tracked route/tier: Vercel AI Gateway
Kimi K2.7-Code HighSpeed
$3,520
Cheapest tracked route/tier: Moonshot AI Kimi
Estimated monthly gap: $20.00. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- No overlapping tracked provider route is sourced for GPT-5.1 Codex Max and Kimi K2.7-Code HighSpeed; plan for SDK, billing, or endpoint changes.
- Kimi K2.7-Code HighSpeed is $2/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- No overlapping tracked provider route is sourced for Kimi K2.7-Code HighSpeed and GPT-5.1 Codex Max; plan for SDK, billing, or endpoint changes.
- GPT-5.1 Codex Max is $2/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
Specs
| Specification | ||
|---|---|---|
| Released | 2025-11-19 | 2026-06-15 |
| Context window | — | 262k |
| Parameters | — | 1T |
| Architecture | - | Mixture of Experts |
| License | Proprietary | MITOSI-approved |
| Openness | Proprietary | Open source |
| Commercial use | Commercial use: conditional | Commercial use: permitted |
| Knowledge cutoff | 2024-09 | - |
Pricing and availability
| Pricing attribute | GPT-5.1 Codex Max | Kimi K2.7-Code HighSpeed |
|---|---|---|
| Input price | $1.25/1M tokens | $1.90/1M tokens |
| Output price | $10/1M tokens | $8/1M tokens |
| Providers |
Capabilities
| Capability | GPT-5.1 Codex Max | Kimi K2.7-Code HighSpeed |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | Yes | Yes |
| Function calling | Yes | Yes |
| Tool use | Yes | Yes |
| Structured outputs | Yes | Yes |
| Code execution | No | No |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
No shared benchmark scores are currently available for this pair.
Deep dive
The capability footprint is close: both models cover vision, multimodal input, reasoning mode, function calling, and tool use. That makes context budget, benchmark fit, and provider maturity more important than a simple checklist. If your application depends on one integration detail, verify it against the provider route you plan to use, not just the base model listing.
For cost, GPT-5.1 Codex Max lists $1.25/1M input and $10/1M output tokens on the cheapest tracked provider, while Kimi K2.7-Code HighSpeed lists $1.90/1M input and $8/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Kimi K2.7-Code HighSpeed lower by about $0.15 per million blended tokens. Availability is 1 providers versus 1, so concentration risk also matters.
Choose GPT-5.1 Codex Max when coding workflow support and lower input-token cost are central to the workload. Choose Kimi K2.7-Code HighSpeed when coding workflow support are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship. This keeps the decision grounded in measurable tradeoffs instead of brand-level assumptions. It also helps separate model capability from provider packaging, which can change cost and latency.
FAQ
Which is cheaper, GPT-5.1 Codex Max or Kimi K2.7-Code HighSpeed?
Kimi K2.7-Code HighSpeed is cheaper on tracked token pricing. GPT-5.1 Codex Max costs $1.25/1M input and $10/1M output tokens. Kimi K2.7-Code HighSpeed costs $1.90/1M input and $8/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is GPT-5.1 Codex Max or Kimi K2.7-Code HighSpeed open source?
GPT-5.1 Codex Max is listed under Proprietary. Kimi K2.7-Code HighSpeed is listed under MIT. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for vision, GPT-5.1 Codex Max or Kimi K2.7-Code HighSpeed?
Both GPT-5.1 Codex Max and Kimi K2.7-Code HighSpeed expose vision. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Which is better for multimodal input, GPT-5.1 Codex Max or Kimi K2.7-Code HighSpeed?
Both GPT-5.1 Codex Max and Kimi K2.7-Code HighSpeed expose multimodal input. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Which is better for reasoning mode, GPT-5.1 Codex Max or Kimi K2.7-Code HighSpeed?
Both GPT-5.1 Codex Max and Kimi K2.7-Code HighSpeed expose reasoning mode. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Where can I run GPT-5.1 Codex Max and Kimi K2.7-Code HighSpeed?
GPT-5.1 Codex Max is available on Vercel AI Gateway. Kimi K2.7-Code HighSpeed is available on Moonshot AI Kimi. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-06-22. Data sourced from public model cards and provider documentation.