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Step 5 Preview
● live- Released
- September 20, 2026
- Bench index
- 33.3 · #30 of 45
The watchers keep tracking it: lineup changes, pricing moves and deprecations all alert.
Launch details
Live — Sep 20; 600B total / ~27B active MoE; 1M ctx; $1.00/$2.70 per 1M, $0.05 cached input; open weights landed Oct 15, as scheduled: FP8 and BF16 checkpoints on Hugging Face and ModelScope, plus an NVFP4 build on Hugging Face (604.3B parameters in the safetensors index; about 650 GB in FP8, 1.2 TB in BF16), under the StepFun Model License 1.0, which adds a 'Powered by StepFun AI' credit past 100M monthly users or $20M monthly revenue and a separate commercial license for device makers and for model-as-a-service firms over $20M a year (license read Oct 15); aimed at long-horizon agentic work.Answering in 1.6s· answered Live model status →
Watch for StepFun’s next model, free →Launch report (PDF)
Timeline
StepFun released the weights of Step 5 Preview on October 15, the date it set when the model went on sale through its API on September 20. FP8 and BF16 checkpoints are on Hugging Face and ModelScope, and an NVFP4 build is on Hugging Face too.
On the bench index
Coding leaderboard
#34 of 45 on the coding index, at 30 · combines LMArena · Coding, LiveBench · Coding, Vals Vibe Code Bench
Open weights
#6 of 16 open-weights models on the Bench Index · stepfun-ai/Step-5-Preview on Hugging Face · 604B parameters · license custom (stepfun-model-license)
Where to use Step 5 Preview
21 providers list Step 5 Preview in the models.dev catalog (as of 2026-11-05), under the model ids shown below.
stepfun/step-5-previewstepfun/step-5-previewstepfun/step-5-previewstep-5-previewstepfun/Step-5-Previewstepfun-ai/Step-5-Previewstep-5-previewdeepinfra/stepfun-ai/Step-5-Preview · tencent/step-5-previewstep-5-previewstepfun/step-5-previewtencent/step-5-previewstepfun/step-5-previewAlso listed by Novita AI, Nvidia, OpenCode, OpenCode Go, Requesty, StepFun (China), StepFun (Global), StepFun Step Plan (China), StepFun Step Plan (Global).
Listings cover the model family, so a provider may list a sibling tier under the same name. Check the id before you build on it.
Step 5 Preview: quick answers
Is Step 5 Preview out?
Yes. Step 5 Preview is live and has been since September 20, 2026.
When was Step 5 Preview released?
September 20, 2026.
Is Step 5 Preview good for coding?
On the ArtificialWatch coding index it scores 30, #34 of 45 ranked models. The index combines LMArena · Coding, LiveBench · Coding and Vals Vibe Code Bench, taking the median of each model's percentile across them.
Is Step 5 Preview open source?
It has open weights: the trained model is public on Hugging Face as stepfun-ai/Step-5-Preview, 604B parameters as Hugging Face counts them, license custom (stepfun-model-license). Among the 16 open-weights models the ArtificialWatch Bench Index ranks, it is #6.
Who makes Step 5 Preview?
StepFun. ArtificialWatch also tracks Step 3.8 Flash and Step 6 from StepFun.
Where can I use Step 5 Preview?
21 providers list it in the models.dev catalog, including OpenRouter, Vercel AI Gateway, AI/ML API, AIHubMix and CommandCode. The exact model ids each one lists are on this page.
Is Step 5 Preview open weights?
Yes. Step 5 Preview is released with open weights.
More from StepFun
Cite this page
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<a href="https://artificialwatch.com/model/step-5">Step 5 Preview on ArtificialWatch</a>ArtificialWatch, "Step 5 Preview", https://artificialwatch.com/model/step-5Know when StepFun's next model drops. Free.
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