Claude 3.5 Sonnet v2 vs Step 3.7 Flash
Claude 3.5 Sonnet v2 (2025) and Step 3.7 Flash (2026) are frontier reasoning models from Anthropic and StepFun. Claude 3.5 Sonnet v2 ships a 200k-token context window, while Step 3.7 Flash ships a 256k-token context window. On pricing, Step 3.7 Flash costs $0.20/1M input tokens versus $6/1M 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.
Step 3.7 Flash is ~2900% cheaper at $0.20/1M; pay for Claude 3.5 Sonnet v2 only for vision-heavy evaluation.
Decision scorecard
Local evidence first| Signal | Claude 3.5 Sonnet v2 | Step 3.7 Flash |
|---|---|---|
| Best for | multimodal apps and provider-routed production | reasoning-heavy apps, multimodal apps, and tool-calling agents |
| Decision fit | RAG, Long context, and Vision | Coding, RAG, and Agents |
| Context window | 200k | 256k |
| Cheapest output | $30/1M tokens | $1.15/1M tokens |
| Provider routes | 2 tracked | 3 tracked |
| Shared benchmarks | 0 shared | 0 shared |
Decision tradeoffs
- Local decision data tags Claude 3.5 Sonnet v2 for RAG, Long context, and Vision.
- Step 3.7 Flash has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Step 3.7 Flash has the lower cheapest tracked output price at $1.15/1M tokens.
- Step 3.7 Flash has broader tracked provider coverage for fallback and route flexibility.
- Step 3.7 Flash uniquely exposes Reasoning and JSON / Tool use in local model data.
- Local decision data tags Step 3.7 Flash 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.
Claude 3.5 Sonnet v2
$12,300
Cheapest tracked route/tier: AWS Bedrock
Step 3.7 Flash
$448
Cheapest tracked route/tier: StepFun
Estimated monthly gap: $11,853. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- No overlapping tracked provider route is sourced for Claude 3.5 Sonnet v2 and Step 3.7 Flash; plan for SDK, billing, or endpoint changes.
- Step 3.7 Flash is $28.85/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Step 3.7 Flash adds Reasoning and JSON / JSON / Tool use in local capability data.
- No overlapping tracked provider route is sourced for Step 3.7 Flash and Claude 3.5 Sonnet v2; plan for SDK, billing, or endpoint changes.
- Claude 3.5 Sonnet v2 is $28.85/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Check replacement coverage for Reasoning and JSON / JSON / Tool use before moving production traffic.
Specs
| Specification | ||
|---|---|---|
| Released | 2025-12-01 | 2026-05-29 |
| Context window | 200k | 256k |
| Parameters | — | 198B (11B active) |
| Architecture | - | 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 | 2024-04 | - |
Pricing and availability
| Pricing attribute | Claude 3.5 Sonnet v2 | Step 3.7 Flash |
|---|---|---|
| Input price | $6/1M tokens | $0.20/1M tokens |
| Output price | $30/1M tokens | $1.15/1M tokens |
| Providers |
Capabilities
| Capability | Claude 3.5 Sonnet v2 | Step 3.7 Flash |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | No | Yes |
| JSON / Tool use | No | 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.
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Last reviewed: 2026-07-26. Data sourced from public model cards and provider documentation.