Step 3.5 Flash
StepFun · Mid
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....
Input / 1M
$0.09
Output / 1M
$0.3
Cached input / 1M
$0.02
Context window
262K
Where it sits
46th-cheapest mid model
by blended $/Mtok among 262 listed mid models
75% below the mid median
blended $/Mtok across 262 mid models
Output costs 3.3× input
$0.09 in / $0.3 out per 1M
Cached input saves 78%
$0.02 vs $0.09 per 1M fresh
Held flat since launch (Jun 2026)
no blended price change recorded
Computed live from current prices and this model's history — not hand-written, so it stays accurate as prices move.
Price history
Only one price on record so far — the history chart appears once a price changes.
Snapshots
| Effective | Input | Output | Cached in | Note | Source |
|---|---|---|---|---|---|
| 11 Jun 2026 | $0.09 | $0.3 | $0.02 | Imported from OpenRouter | openrouter.ai |