Kimi K2.5 vs Step 3.5 Flash
Kimi K2.5 (2026) and Step 3.5 Flash (2026) compare a coding-specialized model against a standalone API model. Kimi K2.5 ships a 256k-token context window, while Step 3.5 Flash ships a 256k-token context window. On SWE-bench Verified, Kimi K2.5 leads by 2.4 pts. On pricing, Step 3.5 Flash costs $0.10/1M input tokens versus $0.44/1M for the alternative. This page treats the result as workflow and deployment fit, not a universal model winner.
Treat this as a product-type comparison: Kimi K2.5 is coding-specialized model, while Step 3.5 Flash is standalone API model. Choose based on workflow fit before reading any benchmark or price row as decisive.
Decision scorecard
Local evidence first| Signal | Kimi K2.5 | Step 3.5 Flash |
|---|---|---|
| Product type | Coding-specialized model | Standalone API model |
| Best for | custom coding agents, code generation, and tool loops | reasoning-heavy apps |
| Decision fit | Coding, RAG, and Agents | Coding, Agents, and Long context |
| Context window | 256k | 256k |
| Cheapest output | $2/1M tokens | $0.30/1M tokens |
| Provider routes | 10 tracked | 1 tracked |
| Shared benchmarks | SWE-bench Verified leader | 3 shared |
Decision tradeoffs
- Kimi K2.5 holds a shared-benchmark lead on SWE-bench Verified, ahead by 2.4 points.
- Kimi K2.5 has broader tracked provider coverage for fallback and route flexibility.
- Kimi K2.5 uniquely exposes Vision, Multimodal, and JSON / Tool use in local model data.
- Local decision data tags Kimi K2.5 for Coding, RAG, and Agents.
- Step 3.5 Flash holds a shared-benchmark lead on AIME 2025, ahead by 1.2 points.
- Step 3.5 Flash has the lower cheapest tracked output price at $0.30/1M tokens.
- Step 3.5 Flash uniquely exposes Reasoning in local model data.
- Local decision data tags Step 3.5 Flash for Coding, Agents, and Long context.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
Kimi K2.5
$852
Cheapest tracked route/tier: OpenRouter
Step 3.5 Flash
$155
Cheapest tracked route/tier: OpenRouter
Estimated monthly gap: $697. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on OpenRouter; start route-level A/B tests there.
- Step 3.5 Flash is $1.70/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Vision, Multimodal, and JSON / Tool use before moving production traffic.
- Step 3.5 Flash adds Reasoning in local capability data.
- Provider overlap exists on OpenRouter; start route-level A/B tests there.
- Kimi K2.5 is $1.70/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Check replacement coverage for Reasoning before moving production traffic.
- Kimi K2.5 adds Vision, Multimodal, and JSON / Tool use in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-03-15 | 2026-01-29 |
| Context window | 256k | 256k |
| Parameters | 1T (MoE, 384 experts) | 196B (11B active) |
| Architecture | Mixture of Experts | Mixture of Experts |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Weights | Not released | Not released |
| Code | Unknown | Unknown |
| Commercial use | Commercial use: conditional | Commercial use: conditional |
| Knowledge cutoff | - | - |
Pricing and availability
| Pricing attribute | Kimi K2.5 | Step 3.5 Flash |
|---|---|---|
| Input price | $0.44/1M tokens | $0.10/1M tokens |
| Output price | $2/1M tokens | $0.30/1M tokens |
| Providers |
Capabilities
| Capability | Kimi K2.5 | Step 3.5 Flash |
|---|---|---|
| Vision | Yes | No |
| Multimodal | Yes | No |
| Reasoning | No | Yes |
| JSON / Tool use | Yes | No |
| Structured outputs | Yes | No |
| Code execution | No | No |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
| Benchmark | Kimi K2.5 | Step 3.5 Flash |
|---|---|---|
| SWE-bench Verified | 76.8 | 74.4 |
| AIME 2025 | 96.1 | 97.3 |
| LiveCodeBench | 85.0 | 86.4 |
Continue comparing
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Last reviewed: 2026-06-29. Data sourced from public model cards and provider documentation.