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StepFun
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StepFun

@StepFun_ai

Scale-up possibilities for everyone. API Platform: https://t.co/XlaiCy4DGm HuggingFace: https://t.co/isMgbv7XSm

176 Following16.4K Followers682 Posts
  1. StepFun@StepFun_ai
    Introducing Step 5 Preview: Advancing the Pareto Frontier. Step 5 Preview is our new flagship model for agentic work, delivering frontier-level performance across software engineering and professional knowledge work, with particular strength in finance. - 600B total / 27B active MoE, with 1M context + Vision - Substantially lower task cost at comparable intelligence - Broad software engineering capabilities with sustained execution over long horizons Try Step 5 Preview: Model page: Open weights on Oct 15.
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  2. StepFun@StepFun_ai
    Rain couldn't stop the builders. Great conversations at our Step 5 Preview Launch Night with @togethercompute! From long-horizon agents and tool-calling reliability to inference costs and what AI breakthroughs mean for the next wave of startups. Huge thanks to our panelist Dan Fu (@realDanFu · @togethercompute), Mar Hershenson (@MarHershenson · @pearvc), Saoud Rizwan (@sdrzn · @cline), and Joey Wang (@harvey), and everyone who joined us! More to come.
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  3. StepFun@StepFun_ai
    StepFun is at #AGNTCon + #MCPCon North America! 📍 Find us at Booth #24! If you’re attending, stop by to say hi, catch up, and connect with our team. We’d love to exchange ideas with fellow builders and explore the future of AI agents together. See you there! 🤝
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  4. StepFun@StepFun_ai
    StepFun
    RT @togethercompute: sf, join us this thursday for step 5 preview launch night with stepfun we’ll dig into the model, building + serving agent workloads, and what’s worth building as models keep improving, with dan fu, hongyu zhou, mar hershenson, saoud rizwan, joey wang rsvp:
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  5. StepFun@StepFun_ai
    What a weekend at LA Hacks 2026! Beyond connecting with the community at our booth, we hosted a hands-on workshop to help participants get started with Step 5 Preview and explore what they could build with it. We also launched the StepFun Challenge and saw teams made especially thoughtful and effective use of our models. Huge thanks to everyone who stopped by, joined our workshop, or took on the challenge. Congrats to our three winning teams! We loved being part of LA Hacks and can't wait to see what you build next.
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  6. StepFun@StepFun_ai
    Step 5 Preview weights are out. Now let’s meet in SF.🍷 Join @StepFun_ai and @togethercompute for Step 5 Preview Launch Night & AI Founders Meetup on Thu, Oct 22. On stage: Hongyu Zhou (@StepFun_ai), Dan Fu (@realDanFu · @togethercompute), Mar Hershenson (@MarHershenson · @pearvc), Saoud Rizwan (@sdrzn · @cline), and Joey Wang (@harvey). A first look at Step 5 Preview, live Q&A, and a panel on what's still worth building as AI models get better. Food, drinks & great conversations. A first look at Step 5 Preview, live Q&A, and a panel on what's still worth building as AI models get better. Food, drinks & great conversations. Want to join us? Request your spot here:
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  7. StepFun@StepFun_ai
    LA Hacks 2026, here we come! StepFun will be at UCLA on Oct 17–18 to meet builders, exchange ideas, and explore what's possible with Step 5 Preview. We'll also host a workshop on Sat, Oct 17, 8–9 PM PT at James West Alumni Center. Come say hi!
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  8. StepFun@StepFun_ai
    One week since launch, Step 5 Preview is already #2 on OpenRouter's weekly leaderboard, with 19.5T tokens used. It has also held #2 on the daily leaderboard since Oct 10. Thanks to everyone building with us.
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  9. StepFun@StepFun_ai
    StepFun
    RT @togethercompute: congrats to the StepFun team on releasing Step 5 Preview open weights today we’re excited to be a launch partner and to support another StepFun release as they bring Step 5 Preview to developers
    StepFun @StepFun_ai
    Step 5 Preview is now open weights. BF16 and FP8 weights are live on Hugging Face and ModelScope, together with our technical blog. • Sparse MoE: 600B total, 27B active per token • 1M-token context window • Native text and vision input • Built for long-horizon agentic work: coding, software engineering, professional knowledge work and finance Frontier intelligence, open weights. Build what's next. Hugging Face: ModelScope: GitHub:
    020141
  10. StepFun@StepFun_ai
    Step 5 Preview is now open weights. BF16 and FP8 weights are live on Hugging Face and ModelScope, together with our technical blog. • Sparse MoE: 600B total, 27B active per token • 1M-token context window • Native text and vision input • Built for long-horizon agentic work: coding, software engineering, professional knowledge work and finance Frontier intelligence, open weights. Build what's next. Hugging Face: ModelScope: GitHub:
    Download
    8610596997.2K
  11. StepFun@StepFun_ai
    A 1M-token context window, endless possibilities. Excited to see Step 5 Preview live on @DeepInfra! Thanks to the team for making it easier for developers to build with Step 5. What will you build first?
    DeepInfra @DeepInfra
    Step 5 Preview from @StepFun_ai is live on DeepInfra, day zero. 600B open-weight MoE, 27B active. 1M context, text + vision. FP8. $1.00 in / $2.70 out / $0.05 cached per 1M tokens. Built for long-horizon agents: coding, frontend, finance. What would you load into 1M tokens first?
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  12. DeepInfra✓@DeepInfra
    Step 5 Preview from @StepFun_ai is live on DeepInfra, day zero. 600B open-weight MoE, 27B active. 1M context, text + vision. FP8. $1.00 in / $2.70 out / $0.05 cached per 1M tokens. Built for long-horizon agents: coding, frontend, finance. What would you load into 1M tokens first?
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  13. StepFun@StepFun_ai
    Thanks to @radixark for helping power Step 5 Preview in production! Great to see SGLang enabling efficient, scalable inference for real-world workloads. Excited to keep pushing the boundaries together.
    RadixArk @radixark
    Congratulations to @StepFun_ai on Step 5 Preview going open weights! RadixArk is proud to help power StepFun's first-party production API with SGLang at scale. Production inference means great token economics under strict latency requirements. SGLang and its cache-aware routing stack now bring that to Step 5 Preview in proven production traffic. Building with Step 5 Preview? Deploy with SGLang today!
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  14. StepFun@StepFun_ai
    StepFun
    RT @radixark: Congratulations to @StepFun_ai on Step 5 Preview going open weights! RadixArk is proud to help power StepFun's first-party production API with SGLang at scale. Production inference means great token economics under strict latency requirements. SGLang and its cache-aware routing stack now bring that to Step 5 Preview in proven production traffic. Building with Step 5 Preview? Deploy with SGLang today!
    StepFun @StepFun_ai
    Step 5 Preview is now open weights. BF16 and FP8 weights are live on Hugging Face and ModelScope, together with our technical blog. • Sparse MoE: 600B total, 27B active per token • 1M-token context window • Native text and vision input • Built for long-horizon agentic work: coding, software engineering, professional knowledge work and finance Frontier intelligence, open weights. Build what's next. Hugging Face: ModelScope: GitHub:
    020154
  15. StepFun@StepFun_ai
    StepFun
    RT @picocreator: Step 5 Preview: The new pareto frontier of agentic finance is here We ran an experiment: which open model gives the best M&A memo per dollar? We had 6 open models write the same memo for 80 companies, and two other AI judges picked the best
    StepFun @StepFun_ai
    Step 5 Preview is now open weights. BF16 and FP8 weights are live on Hugging Face and ModelScope, together with our technical blog. • Sparse MoE: 600B total, 27B active per token • 1M-token context window • Native text and vision input • Built for long-horizon agentic work: coding, software engineering, professional knowledge work and finance Frontier intelligence, open weights. Build what's next. Hugging Face: ModelScope: GitHub:
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  16. StepFun@StepFun_ai
    Great to see Step 5 Preview live on @FeatherlessAI! Frontier-level intelligence, competitive cost efficiency, and easier access for developers.
    Featherless AI @FeatherlessAI
    Step 5 Preview is here. @StepFun_ai's new open-weights model sets a new Pareto frontier, matching Kimi K3 on the @ArtificialAnlys Intelligence Index! It’s built for long-horizon agent work, with frontier-level results on software engineering and professional knowledge work, especially finance. - 600B sparse MoE, 27B active per token - ~1/6 the cost per task of Claude Opus 5.5, per Artificial Analysis Now on Featherless, served at FP8.
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  17. Featherless AI✓@FeatherlessAI
    Step 5 Preview is here. @StepFun_ai's new open-weights model sets a new Pareto frontier, matching Kimi K3 on the @ArtificialAnlys Intelligence Index! It’s built for long-horizon agent work, with frontier-level results on software engineering and professional knowledge work, especially finance. - 600B sparse MoE, 27B active per token - ~1/6 the cost per task of Claude Opus 5.5, per Artificial Analysis Now on Featherless, served at FP8.
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    915334.1K
  18. StepFun@StepFun_ai
    Great to see Step 5 Preview delivering strong inference performance on NVIDIA GB300. Looking forward to seeing what developers build with it.
    NVIDIA AI @NVIDIAAI
    Congrats to StepFun on Step 5 Preview 🙌 Their largest open weights release. The 600B MoE model is built to handle agent tasks lasting up to 24 hours. The model runs at nearly 8K tokens/sec/GPU on NVIDIA GB300 using NVFP4. NVP4 checkpoint: Deploy with @SGL_project -  or @vLLM_project - Post-train with NeMo Automodel: Run it with NVIDIA NIM using a single command:
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  19. NVIDIA AI✓@NVIDIAAI
    Congrats to StepFun on Step 5 Preview 🙌 Their largest open weights release. The 600B MoE model is built to handle agent tasks lasting up to 24 hours. The model runs at nearly 8K tokens/sec/GPU on NVIDIA GB300 using NVFP4. NVP4 checkpoint: Deploy with @SGL_project -  or @vLLM_project - Post-train with NeMo Automodel: Run it with NVIDIA NIM using a single command:
    Download
    StepFun @StepFun_ai
    Step 5 Preview is now open weights. BF16 and FP8 weights are live on Hugging Face and ModelScope, together with our technical blog. • Sparse MoE: 600B total, 27B active per token • 1M-token context window • Native text and vision input • Built for long-horizon agentic work: coding, software engineering, professional knowledge work and finance Frontier intelligence, open weights. Build what's next. Hugging Face: ModelScope: GitHub:
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  20. StepFun@StepFun_ai
    Posts @StepFun_ai
    Our technical blog, "Inside Step 5 Preview: Architecture and Training for Agentic Work," covers how architecture and training were co-designed for longer, more complex agent tasks: • 92-layer narrow-and-deep architecture for implicit multi-hop reasoning • Sparse GQA to cut million-token context cost, with 8-token block indexing reducing indexing and top-k overhead to 1/8 • FP32 precision on key states plus fine-grained gradient clipping for stable training • Million-scale verifiable environments • RL for long-horizon tasks with context compression built into policy training
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  21. StepFun@StepFun_ai
    Posts @StepFun_ai
    We've also updated Step Code to v0.1.4, our open-source agent harness built around Step 5 Preview. It helps agents keep track of the goal on long, complex tasks, keep making progress, and check against verifiable results whether the job is actually done. Four releases since open-sourcing, about one every 3 working days, mostly driven by community feedback. Thank you to everyone who tried it and shared feedback.
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  22. StepFun@StepFun_ai
    Step 5 Preview now exists where you build. Now live on @OpenRouter. A week of free access is rolling out today across @opencode, @cline , @NousResearch, @kilocode, and more. Flagship-tier intelligence for agentic and professional work, at substantially lower task cost. Keep your workflow. Switch your model. Try Step 5 Preview on OpenRouter:
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  23. StepFun@StepFun_ai
    Posts @StepFun_ai
    We’ll be hosting our Step 5 Preview Launch Night in SF on Oct 22! Come meet the team and see Step 5 Preview in action:
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  24. StepFun@StepFun_ai
    Strong performance, now within reach of more builders through Nous Portal. Step 5 Preview is free to explore for this week.
    Nous Research @NousResearch
    Step 5 Preview from @StepFun_ai is free on Nous Portal for the next week 600B total / 27B active MoE, 1M context, with vision Step 5 Preview scored 33.89 on Hermes Index, the same score as GPT-6 Luna
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  25. Nous Research✓@NousResearch
    Step 5 Preview from @StepFun_ai is free on Nous Portal for the next week 600B total / 27B active MoE, 1M context, with vision Step 5 Preview scored 33.89 on Hermes Index, the same score as GPT-6 Luna
    Download
    746387471.4K