StepFun

What is StepFun?

StepFun, known in Chinese as 阶跃星辰, is an AI company that builds the Step series of language, multimodal and speech models. It exposes them through a platform with a unified API and a no-code AI Studio.

Key capabilities of StepFun

• Step 5 Preview: Next-generation flagship model for real-world tasks.
• Step 3.7 and 3.5 Flash: Faster model variants.
• StepAudio 3: Realtime speech, TTS, generation, music and ASR.
• One API: Language, speech and image models through one integration.
• AI Studio: No-code interface for trying models.
• Step Plan: Subscription service with model routing.

How StepFun works

Developers register on the platform, obtain an API key and call public models with pay-as-you-go billing. The vendor supports standard OpenAI client libraries and REST, with Python and curl examples. Step 3.7 Flash is described by third parties as a 196B-parameter mixture-of-experts model with a 256K context window.

Who uses StepFun?

Developers and companies that want Chinese-developed multimodal and speech models behind an OpenAI-compatible API, plus consumers via StepFun apps.

StepFun pricing

The vendor describes pay-as-you-go billing without listing rates on the page reviewed. Third-party trackers cite Step 3.5 Flash from $0.09 per million input tokens and Step 3.7 Flash at $0.20 input and $1.15 output per million tokens.

StepFun alternatives

Related tools include Vast.ai, DeepInfra, fal, Hyperbolic and Nebius, which host and serve models rather than develop their own Step series.