Grok Code Fast 1 vs Kimi K2.5
Grok Code Fast 1 (2025) and Kimi K2.5 (2026) are agentic coding models from xAI and Moonshot AI. Grok Code Fast 1 ships a 262K-token context window, while Kimi K2.5 ships a 256K-token context window. On pricing, Grok Code Fast 1 costs $0.2/1M input tokens versus $0.38/1M for the alternative. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit.
Grok Code Fast 1 is ~91% cheaper at $0.2/1M; pay for Kimi K2.5 only for coding workflow support.
Specs
| Released | 2025-08-27 | 2026-03-15 |
| Context window | 262K | 256K |
| Parameters | 314B | 1T (MoE, 384 experts) |
| Architecture | mixture of experts | mixture of experts |
| License | Proprietary | MIT |
| Knowledge cutoff | - | - |
Pricing and availability
| Grok Code Fast 1 | Kimi K2.5 | |
|---|---|---|
| Input price | $0.2/1M tokens | $0.38/1M tokens |
| Output price | $1.5/1M tokens | $1.72/1M tokens |
| Providers |
Capabilities
| Grok Code Fast 1 | Kimi K2.5 | |
|---|---|---|
| Vision | ||
| Multimodal | ||
| Reasoning | ||
| Function calling | ||
| Tool use | ||
| Structured outputs | ||
| Code execution |
Benchmarks
No shared benchmark rows are currently sourced for this pair.
Deep dive
The capability footprint differs most on tool use: Grok Code Fast 1. Both models share function calling and structured outputs, so the practical split is not just feature count. Use those differences to decide whether the page is about raw model quality, agentic coding support, multimodal ingestion, or predictable structured API behavior.
For cost, Grok Code Fast 1 lists $0.2/1M input and $1.5/1M output tokens, while Kimi K2.5 lists $0.38/1M input and $1.72/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Grok Code Fast 1 lower by about $0.19 per million blended tokens. Availability is 1 providers versus 7, so concentration risk also matters.
Choose Grok Code Fast 1 when coding workflow support, larger context windows, and lower input-token cost are central to the workload. Choose Kimi K2.5 when coding workflow support and broader provider choice 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 has a larger context window, Grok Code Fast 1 or Kimi K2.5?
Grok Code Fast 1 supports 262K tokens, while Kimi K2.5 supports 256K tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Which is cheaper, Grok Code Fast 1 or Kimi K2.5?
Grok Code Fast 1 is cheaper on tracked token pricing. Grok Code Fast 1 costs $0.2/1M input and $1.5/1M output tokens. Kimi K2.5 costs $0.38/1M input and $1.72/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Grok Code Fast 1 or Kimi K2.5 open source?
Grok Code Fast 1 is listed under Proprietary. Kimi K2.5 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 function calling, Grok Code Fast 1 or Kimi K2.5?
Both Grok Code Fast 1 and Kimi K2.5 expose function calling. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Which is better for tool use, Grok Code Fast 1 or Kimi K2.5?
Grok Code Fast 1 has the clearer documented tool use signal in this comparison. If tool use is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Where can I run Grok Code Fast 1 and Kimi K2.5?
Grok Code Fast 1 is available on OpenRouter. Kimi K2.5 is available on Fireworks AI, OpenRouter, Together AI, Fireworks AI, and NVIDIA NIM. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-04-27. Data sourced from public model cards and provider documentation.