Reasoning Tools JSON Open weights

StepFun's next-generation flagship base model for coding and professional knowledge work, with native text, image, and video input and a 1M-token context window

stepfun/step-5-preview 2026-09-16 1M context $1.046/M input $2.989/M output
17 providers
Reasoning Tools JSON Open weights

Newer StepFun flash model for faster agents, coding, and multimodal prompts

stepfun/step-3.7-flash 2026-05-29 256K context $0.202/M input $1.211/M output
21 providers
Open weights

StepFun flash lane for quick multimodal reasoning and coding assistance

stepfun/step-3.5-flash 2026-01-29 256K context $0.105/M input $0.314/M output
15 providers