StepFun API
Access StepFun instantly with Puter.js, and add AI to any app in a few lines of code without backend or API keys.
// npm install @heyputer/puter.js
import { puter } from '@heyputer/puter.js';
puter.ai.chat("Explain AI like I'm five!", {
model: "stepfun/step-3.5-flash"
}).then(response => {
console.log(response);
});
<html>
<body>
<script src="https://js.puter.com/v2/"></script>
<script>
puter.ai.chat("Explain AI like I'm five!", {
model: "stepfun/step-3.5-flash"
}).then(response => {
console.log(response);
});
</script>
</body>
</html>
List of StepFun Models
StepFun: Step 3.5 Flash
stepfun/step-3.5-flash
Step 3.5 Flash is StepFun's open-source reasoning model built on a sparse Mixture of Experts architecture with 196B total parameters but only 11B active per token. It's optimized for agentic tasks and coding with ultra-fast inference speeds up to 350 tokens per second and supports 256K context length.
ChatStepFun: Step3
stepfun-ai/step3
Step3 is a multimodal reasoning model from StepFun built on a Mixture-of-Experts architecture with 321B total parameters (38B active), designed for cost-effective vision-language reasoning. It features innovative Multi-Matrix Factorization Attention (MFA) and Attention-FFN Disaggregation (AFD) for efficient inference across various hardware. The model excels at visual interpretation, complex reasoning, and is available via API or as open-source checkpoints on Hugging Face.
Frequently Asked Questions
The StepFun API gives you access to models for AI chat. Through Puter.js, you can start using StepFun models instantly with zero setup or configuration.
Puter.js supports a variety of StepFun models, including StepFun: Step 3.5 Flash and StepFun: Step3. Find all AI models supported by Puter.js in the AI model list.
With the User-Pays model, users cover their own AI costs through their Puter account. This means you can build apps without worrying about infrastructure expenses.
Puter.js is a JavaScript library that provides access to AI, storage, and other cloud services directly from a single API. It handles authentication, infrastructure, and scaling so you can focus on building your app.
Yes — the StepFun API through Puter.js works with any JavaScript framework, Node.js, or plain HTML. Just include the library and start building. See the documentation for more details.