Step 3.5 Flash

Pricing — 1 offering(s)

Showing the active price and any recorded history. Full pricing history is available via the paid API — see API docs.

Capability profile

Operator guidance

A strong value pick: frontier-adjacent benchmark numbers (from StepFun's own technical report) at one of the lowest price points in this registry, backed by a real published report rather than marketing claims. Prefer it over pricier flagships when the task tolerates an 11B-active model and cost dominates. Note the report's benchmarks are StepFun-run; no independent third-party reproduction found yet.

Use cases

• Cost- and latency-sensitive agentic and coding workloads that still need frontier-adjacent reasoning quality
• High-throughput production serving where the 11B active footprint keeps per-token cost very low
• Long-context tasks (up to ~256K) at a fast, cheap tier
• Self-hosted deployment (open weights on GitHub)

Limitations

• Benchmarks are from StepFun's own technical report — credible and detailed, but not independently reproduced
• A later model, Step 3.7 Flash (198B MoE, vision-language), exists — this entry is specifically Step 3.5 Flash
• The pricing-page row `step-3.5-flash` is a substring of an adjacent dated `step-3.5-flash-2603` row (see registry note) — harmless while prices match
• Multilingual/instruction-following not separately benchmarked in the report

Citations

• Step 3.5 Flash: Open Frontier-Level Intelligence with 11B Active Parameters (arXiv:2602.10604)
• stepfun-ai/Step-3.5-Flash (GitHub, open weights)
• StepFun developer platform pricing