// StepFun (阶跃星辰)
Step-3.5-Flash
A StepFun (阶跃星辰) model. 3 prices across 2 channels side by side, each with its source and check date – plus specs, licence, speed and benchmarks.
- Official in/out per 1M
- ¥0.7 / ¥2.1
- Lowest (SiliconFlow)
- $0.1 / $0.3
- Context
- 262K
- AA index
- 17
Prices checked 2026-10-22Official sources linked on every rowNo estimatesCheapest LLM APIs →
01Specs at a glance
Official values first; gaps filled from OpenRouter’s API where the vendor page is silent.
| Vendor | StepFun (阶跃星辰) |
|---|---|
| Context window | 262K (262,144 tokens) |
| Max output | 66K |
| Input | Text |
| Output | Text |
| Tool calling / JSON | Yes / No |
| Weights & licence | Open weights · Apache-2.0 · Hugging Face |
| Parameters | 199B (from weight files) |
| Released | Jan 29, 2026 |
| Model IDs | step-3.5-flash · stepfun/step-3.5-flash · stepfun-ai/Step-3.5-Flash |
02Prices on 2 channels
Per 1M tokens, in the currency each source publishes (1 USD = 6.7 CNY for the blended column). Sorted: official first, then cheapest.
| Channel | Source | Input | Output | Cache hit | Blended $ | Context | Notes |
|---|---|---|---|---|---|---|---|
| Official Vendor’s China site, billed in CNY | Official 10-10 | ¥0.7 | ¥2.1 | ¥0.14 | 0.157 | 262K | |
| SiliconFlow · fp8 Via OpenRouter / provider listed there | OpenRouter 10-22 | $0.1 | $0.3 | — | 0.15 | 262K | SiliconFlow price as listed on OpenRouter (pass-through; quantization=fp8; discount field=0); not checked against SiliconFlow's own page |
| SiliconFlow Inference platform (own price page) | Platform 10-10 | ¥0.7 | ¥2.1 | — | 0.157 | — | SiliconFlow (硅基流动) own pricing page |
“Official” = vendor pricing page; “Platform” = the platform’s own pricing page; “OpenRouter” = price listed on OpenRouter, not checked on the platform’s site. Click a source tag to open the original page.
03Where you can use it
Derived only from the price sources above. Country restrictions are set by each vendor – check their terms before you sign up.
- Vendor’s China site, billed in CNY
Official - Via OpenRouter / provider listed there
SiliconFlow - Inference platform (own price page)
SiliconFlow - Self-host the open weights
GPU / VRAM sizing and build plans→
04Performance
Speed and AA index from Artificial Analysis public leaderboards (not our own tests); benchmark scores from our benchmark library, best result per benchmark.
- AA indexStep 3.5 Flash 2603
- 17
- Output speed (median)
- 158 tok/s
- Time to first token
- 3.29s
- AA index per $ (blended)
- 108.25
| Benchmark | Best score | Source | Date |
|---|---|---|---|
| LMArena Text | 1393 | official | 2026-10-08 |
05Price changes we recorded
All price changes →From our daily re-checks of the sources above.
No price change recorded since we started tracking (2026-10-10).
06More from StepFun (阶跃星辰)
FAQ
How much does the Step-3.5-Flash API cost?
On the official pricing page: ¥0.7 / ¥2.1 per 1M input / output tokens, cached input ¥0.14 (checked 2026-10-10). The lowest price we found is $0.1 / $0.3 on SiliconFlow.
What is the context window of Step-3.5-Flash?
262K tokens of context, up to 66K output tokens. Platforms may cap it lower – see the table.
Is Step-3.5-Flash open source?
Yes, the weights are published on Hugging Face (stepfun-ai/Step-3.5-Flash). Licence: Apache-2.0.