StepFun

⚡️ Step 3.5 Flash is coming: Fast Enough to Think. Reliable Enough to Act！ We’re dropping our most capable open-source foundation model yet. Frontier reasoning meets extreme efficiency. It leverages a sparse Mixture of Experts (MoE) architecture, 196B total → 11B active. Key Capabilities: ✅Reasoning at Speed: MTP-3 powered throughput at 100–300 tok/s (350 tok/s peak for single-stream coding tasks). ✅Agentic Power: ⚡️ 74.4% SWE-bench Verified ⚡️ 51.0% Terminal-Bench 2.0. Proven stability for complex, long-horizon tasks. ✅256K Efficient Context: 3:1 SWA ratio + Full Attention. Massive datasets or long codebases support with minimal overhead. Consistent performance, hybrid efficiency. ✅Local-First Deployment: Optimized for Mac Studio M4 Max, NVIDIA DGX Spark. Secure, private, and frontier-capable. Your data, your hardware, your agent. You can try Step 3.5 Flash right now: 👉 OpenRouter: openrouter.ai/stepfun/step-3… 👉 GitHub: github.com/stepfun-ai/Ste… 👉 HuggingFace：huggingface.co/stepfun-ai/Ste… 👉 Blog：static.stepfun.com/blog/step-3.5-… 👉 ModelScope: modelscope.cn/models/stepfun… 🌌 The Next：Step 4 training is officially LIVE！ We're calling on the world's boldest builders to co-creat the Step 4 right now. Let's define the Agentic Era together! Join our Discord：discord.gg/RcMJhNVAQc

Step 3.5 Flash is now live on @gg_lemonade — free & unlimited for 14 days! 🎮 Lemonade is a coding agent built for making Roblox games. Try it free → lemonade.gg (select Step 3.5 Flash as your model)

StepAudio 2.5 ASR is here! 4x faster decoding. 30-minute continuous audio. $0.022/hour. We built this to push ASR further — faster inference, longer inputs, bilingual accuracy that holds up, and a price point that actually scales. ⚡ 4x decoding speed vs. previous generation ⚡ 30-min continuous audio processing ⚡ Top-tier bilingual (EN/ZH) performance ⚡ 80% lower inference cost — API at $0.022/hr For more details, check out: - Documentation: platform.stepfun.ai/docs/en/guides… - Demos: stepaudiollm.github.io/step-audio-2.5… - Model card: stepaudiollm.github.io/step-audio-2.5…

Step 3.5 Flash⚡ now live on @NousResearch Portal, free for 10 days! Big thanks to the Nous team, it’s been awesome working with you. Excited to see what the community ships🔥

Docs: - Standard API: platform.stepfun.ai/docs/en/api-re… - Step Plan: platform.stepfun.ai/docs/en/step-p…

StepAudio 2.5 TTS is live now! Control emotion, pacing, pauses, and delivery with plain natural language. No tags, no preset combos. Just describe what you want the voice to do. Zero-shot voice cloning with full timbre + emotion control. Available via Pay-as-you-go API or Step Plan.

See more demos and learn more about the model here: stepaudiollm.github.io/step-audio-2.5…

Also free in KiloClaw for those building agentic pipelines there!

Glad to see Step 3.5 Flash finding its home in agentic workflows. Thanks @kilocode pick it from the model dropdown and build something! try it: kilo.codes/flash-free

ACE-Step 1.5 XL is now open-source! a 4B DiT decoder for music generation, available in three variants. Runs from 12GB VRAM (INT8 offload) to 24GB full quality. MIT license, commercial-safe training data.

Step 3.5 Flash 2603 just shipped! Low mode: 56% fewer tokens High mode: full reasoning, still 14% leaner than before Agentic workflows make hundreds of calls—most don't need deep thinking. Not every call needs to be a philosophy session. Now you can dial it down. Live for all Step Plan users. platform.stepfun.ai/step-plan

StepFun models are now in @openclaw!! Official plugin on ClawHub — Standard API or Step Plan, CN, and international endpoints are both supported. v3.28+ required. One install, you're set.

Quick update! Thanks to everyone using Step 3.5 Flash. The response has been amazing. For those who want more: paid channels now get a dedicated fast lane at 100+ tokens/s — that includes Step Plan and OpenRouter paid API. Free tier speed stays as is. When you're ready to go faster, Step Plan starts at $6.99/mo. platform.stepfun.ai/step-plan

Step Plan is now live on StepFun Open Platform!! Affordable OpenClaw and coding, all month. What you get: ⚡ Step 3.5 Flash, fast inference on every tier. 🔧 Works with Cursor, Windsurf, Cline, and your own stack. Zero lock-in. 💰 Four tiers from $6.99/mo to $99/mo. 🔜 Multimodal flagship coming to the plan soon. Check it out at: platform.stepfun.ai/step-plan

@_blackcat1402 Thanks for the love! Step Plan just went live — check it out: platform.stepfun.ai/step-plan

@StepFun_ai you are the new open source king and hope you continue open source while others are closing source; At least hold on until the stock goes public successfully. Please launch coding plan asap. I believe many open-source believers like me are eagerly awaiting it.

our SFT dataset is now on @ModelScope2022 too! modelscope.cn/datasets/stepf…

the last missing piece. our SFT training dataset is now available at huggingface.co/datasets/stepf…

great to see teams building on Step 3.5 Flash in production 🔨

@mudler_it awesome to hear! welcome aboard 🔨 let us know if there's anything we can help with during the switch.

Another update from my team: we are switching to Step 3.5 Flash as base! great model for its size! For my use it completely destroys Qwen 3.5 122b! reports.localai.io/posts/step-3.5…