StepFun, the Chinese lab whose Step-3.x generation shipped Apache-2.0 open weights, put its next flagship behind the API on September 18 — and the independent numbers make it a pricing story first. Artificial Analysis ran the model itself and scores Step 5 Preview 44 on its Intelligence Index (25th of 200 models, against a 25 median) and 27th by cost, priced at $1.00 in / $2.70 out per million tokens with a 1M-token context and image input. For the operator, that is the current reasoning tier at roughly half the median input price and a quarter of the median output price — benchmarked, not launch-blurbed — which makes it the cheapest live experiment on how far the “good enough” line has moved. The tell is the weights: no Step 5 release exists on StepFun’s public model repo, so the same lab that gave away Step-3.x is now charging for its best model. The Beijing price curve and the closed-lane curve kept crossing in opposite directions — and just did it again.
Source: artificialanalysis.ai, huggingface.co
What I’m watching
Whether a Step 5 release follows on the open lane — the Step-3.x pattern says the flash-size distillate eventually ships — because the which-lane decision is the story as much as the capability. If the cheapest frontier capability stays API-only, the open-vs-closed ledger moved this week rather than later, and the price-compression thread this column has been running since the speed-limit week gets a new rent schedule.