MODEL PROOF
Step 3.5 Flash
BETTER VALUE OPTION
A stored alternative has an equal-or-higher measured score and an equal-or-lower price.
Hy3 · Δ score 36.9 points · 4% lower measured price · $0.144 / 1M tokens
- Independent LMArena score
- 1,403.7 ± 3.6 · 57,137 votes
- Context window
- 262.14K
- Maximum output
- 65.54K
- Input modalities
- text
- Output modalities
- text
- Published input price
- $0.100 / 1M tokens
- Published output price
- $0.300 / 1M tokens
- Pricing kind
- fixed
Inspect complete billing conditions and endpoint terms below.
Every price dimension · USD per million tokens
| Input | $0.100/M |
|---|---|
| Output | $0.300/M |
| Cached input | Unknown/M |
| Cache write | Unknown/M |
| Cache write 1h | Unknown/M |
| Reasoning | Unknown/M |
Who sells it
The same weights, different shops. Cheapest is not like-for-like when serving precision differs.
1 provider offers · rates, limits and conditions
Rates are USD per million tokens. Endpoint terms can differ even when the quoted price and precision match. A listed parameter is a provider declaration, not a task-success test.
| Seller | Input | Output | Precision | Uptime (1d) |
|---|---|---|---|---|
| SiliconFlowsiliconflow/fp8 Endpoint terms
| $0.100 | $0.300 | fp8 | 99.99% |
Independent scores
| LMArena Elo | 1403.7default |
|---|
LMArena Elo under CC BY 4.0. Absence of another board is not a score of zero.
Capability
| Context window | 262K |
|---|---|
| Max output | 66K |
| Input modes | text |
| Tool use | yes |
| Reasoning | always on |
| Open weights | Unknown |
Provenance
| Price source | openrouter.ai |
|---|---|
| Fetched | 2026-09-23 |
| Quality data | verified |
People search StepFun. This is Step 3.5 Flash, which has an LMArena score in this catalogue. Step 3.7 Flash is a different, unrated SKU.
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....
Questions this page answers
What does Step 3.5 Flash cost?
$0.100/M in, $0.300/M out in this catalogue, as of the fetch date on this page. That is the API row, not a subscription.
Does Step 3.5 Flash have an independent quality score?
Step 3.5 Flash has an LMArena score in this catalogue.
What beats Step 3.5 Flash?
Hy3 has an equal-or-higher measured score and an equal-or-lower price.
Does this page use Artificial Analysis scores for Step 3.5 Flash?
No. Artificial Analysis figures are not published here. Quality on this page is LMArena Elo where a score exists; otherwise the row is unrated.
MODEL MONUMENT
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The verdict as one SVG, for a README or a docs page. It states this model's dominance status at the balanced workload on the LMArena lens, with the date it was computed, and it is rebuilt with the catalogue — so it changes when the verdict changes, including to one you would rather it did not.
[](https://undominated.ai/models/stepfun__step-3.5-flash/)<a href="https://undominated.ai/models/stepfun__step-3.5-flash/"><img src="https://undominated.ai/badge/stepfun__step-3.5-flash.svg" alt="Step 3.5 Flash — Undominated.ai dominance verdict" height="36"></a>Direct file: https://undominated.ai/badge/stepfun__step-3.5-flash.svg — a static SVG, written by scripts/build-badges.mjs on every build, so the copy you embed is never
older than the last deploy.
