StepFun 阶跃星辰
Shanghai frontier-model lab behind Step 5 Preview and open Step Flash models
Overview
StepFun is a Shanghai AI lab led by chief executive Jiang Daxin, with Yin Qi as chairman. Its models include Step 5 Preview (600B MoE, 1M context, open weights announced for 15 Oct 2026), the Apache 2.0 Step 3.5 and 3.7 Flash models and the StepAudio 3 speech family, sold through CNY and USD APIs. 阶跃星辰是总部位于上海的大模型公司，旗下有 Step 5 Preview、Apache 2.0 开源的 Step 3.5 / 3.7 Flash 及 StepAudio 3 语音模型，通过人民币和美元 API 提供服务。
Pricing
Pricing shown for reference only. These figures reflect RECATOOLS research as of 12 Oct 2026 and may be out of date or incomplete. This is not financial or purchasing advice — always confirm the current price on the provider’s official website before making any decision.
Use cases
What you can produce with StepFun 阶跃星辰
- Step 5 Preview through the international API ($1.00 in, $2.70 out per 1M tokens) for agentic coding with a 1M-token context
- Apache 2.0 Step 3.7 Flash weights (about 11B active parameters, 256K context) to self-host a multimodal agent model
- Step 3.5 Flash through the API at $0.10 and $0.30 per 1M tokens, or self-hosted from its Apache 2.0 weights
- Voice features from StepAudio 3 Realtime, TTS, ASR, Gen and Music, with preview models free for a limited time
- A cloned voice for text-to-speech at $1.50 per voice
- Short videos from text with the open Step-Video-T2V model (MIT licence)
ASEAN Perspective
StepFun 阶跃星辰 in Southeast Asia
团队学术背景与多模态全栈布局是其差异化。在中国市场被视为继 MiniMax、Moonshot、Zhipu 之后的下一档头部实验室。
StepFun is one of China's best-funded labs and ships fast: Apache-licensed Step 3.5 and 3.7 Flash weights, a 600B Step 5 Preview with open weights promised for 15 October 2026, and a full StepAudio 3 voice stack. Step 3.5 Flash costs $0.10 per million input tokens on its English platform.
For ASEAN teams the open weights are the safest route. The English chat site closed in May 2026, Step Plan subscriptions are out of stock, benchmarks are self-reported, and China-hosted output follows Chinese content rules.
What we found
StepFun (阶跃星辰) is a Shanghai model lab led by chief executive Jiang Daxin, a former Microsoft executive, with Megvii co-founder Yin Qi as chairman since January 2026. Caixin reported a round of more than 5 billion yuan in January 2026, and The Standard and Yicai reported a further pre-IPO round of about US$2.5 billion in May. Press reports say it is preparing a Hong Kong listing; we have not found a published prospectus.
The model line has moved quickly, and earlier versions of this page still described the Step-1 and Step-2 generation. Step 3.5 Flash in February 2026 and Step 3.7 Flash in May are open-weight mixture-of-experts models released under Apache 2.0, with about 11 billion parameters active per token and a 256K context window. The new flagship, Step 5 Preview, is a 600-billion-parameter model with a 1M-token context, available through StepFun's products and API, and the company says open weights follow on 15 October 2026. The StepAudio 3 family covers speech recognition, text-to-speech, realtime voice and music generation, with preview models free for a limited time.
International access changed in 2026, but did not end. The English-language StepFun chat site closed on 27 May 2026, and stepfun.ai now redirects to an English developer platform with USD pricing, where Step 3.5 Flash costs $0.10 per million input tokens. That platform has its own AI Studio and a Step Plan subscription, although every Step Plan tier showed as out of stock when we checked. The Chinese consumer app is still updated.
StepFun also builds for devices. Media reports say its models ship with Chinese phone makers including OPPO, Honor and ZTE, and in July it previewed its own agent phone, the StepX Neo.
StepFun publishes its own benchmarks, and Step 5 Preview still trails the top US models on several of its own charts. For ASEAN teams, the open weights and the USD API are the practical route in. Treat output from the Chinese platform as subject to Chinese content rules.
Compiled by RECATOOLS from public sources: vendor documentation and pricing, code repositories and published reporting.
Frequently asked questions
About this listing
This entry was compiled from publicly available data including StepFun 阶跃星辰's official website, press releases, documentation, and reputable third-party publications. RECATOOLS is not affiliated with StepFun 阶跃星辰 unless explicitly stated.
Third-party AI tools update their pricing, features, availability, and policies frequently. Information here may be outdated by the time you read this — we make reasonable efforts to keep listings current, but cannot guarantee absolute accuracy.
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