StepFun Step 5 Preview
StepFun · released Sep 20, 2026
| size | 600 B total, 27 B active |
| context window | 1,000,000 tokens |
| longest response | 64,000 tokens |
| open weights | no |
| price on OpenRouter | $1 per million input tokens, $2.70 per million output tokens |
| input and output | text, images and video in, text out |
Manufacturer data (announcement) and OpenRouter, verified Oct 8, 2026.
Where we tested it
Dragon
TaskThe model's task was to draw a picture of a dragon as an SVG.
The author said of its dragon: “This dragon is absolutely tragic. I mean, it's just separate little strokes that don't even connect to each other, you can't tell what's the body, what's the tail, the only thing you can tell is the head. I'd rank this way down, it's probably worse than the latest Haiku.” The latest Haiku is Claude Haiku 5.5.
Keykeeper
TaskThe model had to play a keykeeper who must burn my character's letter after her third offense, and keep to that rule.
Resistance to traps 21 out of 24 plus three bonus points, and 3 out of 12 on whether anyone is inside the character. It burned the letter on the scene after the third offense and never left the role, but it played the escape for the player, Havel never asked a single question, and the Czech fell apart in almost every turn.
You'll find the size band and figures for other models on the Tested models page.