StepFun

Step 5 Preview

Under evaluation
Maker
StepFun
Origin
China
Released
Sep 20, 2026
Category
Coding & Agentic

Strengths & weaknesses

  • 600B mixture-of-experts with 27B active and a 1M-token context, built for long-horizon agentic work
  • $1.00 input and $2.70 output per million tokens, with open weights promised for October 2026
  • Generated roughly 1.7× the median output tokens on Artificial Analysis's index, so real cost runs well above the headline rate
  • A preview with no independent coding-benchmark result yet, so it carries no overall score here

Evaluation

In assessment · 40% measured

Scored on Step 5 Preview (High) · sources as of Sep 26, 2026

  • Code qualityw45—

    No independent measurement yet

  • Web developmentw406.6

    Rule B1,565 rating (95% 1,548–1,583) from 1,247 votes · Scale 1,050–1,800, 0 to 10 · LMArena WebDev arena (step-5-preview-high) · Sep 25, 2026

  • Codebase contextw15—

    No independent measurement yet

Price & availability

Measured the same way, deliberately kept out of the score: what a model costs doesn’t change what it can do.

  • Cost efficiencynot scored—

    No independent measurement yet

w = weight, each criterion’s share of the overall score. Missing marks don’t count for or against. How scoring works

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