StepFun: Step 5 Preview

StepFun: Step 5 Preview is a preview-stage model from StepFun that accepts text, image, and video input and returns text. It offers a 1,000,000-token context window with up to 64,000 completion tokens, so long documents, large codebases, or lengthy transcripts can fit in a single request. It supports tool calling and a reasoning mode. The listing does not document structured output support or whether the weights are open, so confirm both before relying on them. At $1.00 per million input tokens and $2.70 per million output tokens, it suits teams that need long-context multimodal input without paying top-tier rates, particularly for workloads dominated by input. Its blended benchmark score of 74.2 (AI Index 72.2) comes from a single independent benchmark, which is too thin to establish its standing against alternatives. Shortlist it for testing on your own tasks rather than choosing it on published results alone.