stepfun Open weights Reasoning

Step 3.5 Flash pricing & benchmarks

Released Jan 29, 2026 · served by 1 provider

Input / 1M tokens$0.100
Output / 1M tokens$0.300
Context window262K
Cached input
1M in + 300K out$0.19

What Step 3.5 Flash is

Step 3.5 Flash is StepFun's most capable open-source foundation model. Built on a sparse Mixture of Experts (MoE) architecture, it selectively activates only 11B of its 196B parameters per token....

Providers and prices for Step 3.5 Flash

The same model costs different amounts depending on who serves it. Prices are per 1M tokens, cheapest first. Uptime and throughput are OpenRouter's rolling measurements, not vendor claims.

ProviderInputOutputContext QuantUptime 24hThroughput
SiliconFlowcheapest $0.100 $0.300 262K fp8 100.0%

FAQ

How much does the Step 3.5 Flash API cost?

$0.100 per 1M input tokens and $0.300 per 1M output tokens. A typical workload of 1M input + 300K output tokens costs about $0.19.

Is Step 3.5 Flash free?

No. It is a paid model starting at $0.100 per 1M input tokens, though some providers offer trial credits.

Which provider is cheapest for Step 3.5 Flash?

SiliconFlow at $0.100 input / $0.300 output per 1M tokens (fp8 quantization).

Can I self-host Step 3.5 Flash?

Yes — weights are published as stepfun-ai/Step-3.5-Flash on Hugging Face, so you can run it on your own hardware.