Free, Unlimited StepFun AI API
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In this tutorial, you will learn how to add StepFun Step 3.5 Flash into your application for free using Puter.js. You can gain access to various AI models using Puter.js without having to set up the AI server yourself.
Puter.js uses the User-Pays model, where users of your application cover their own AI costs. This means you as a developer don't pay anything for your users' usage, making your app practically free to run. You can scale to unlimited users and pay nothing for the AI or server usage.
Getting Started
Add Puter.js to your project with a single line:
<script src="https://js.puter.com/v2/"></script>
That's it, you're ready to start integrating Step 3.5 Flash into your application.
Example 1: Basic Chat
Step 3.5 Flash is built on a sparse Mixture of Experts architecture with 196B total parameters but only 11B active per token, delivering ultra-fast inference speeds up to 350 tokens per second.
<html>
<body>
<script src="https://js.puter.com/v2/"></script>
<script>
puter.ai.chat(
"What are the key benefits of Mixture of Experts architectures in modern AI models?",
{ model: "stepfun/step-3.5-flash:free" }
)
.then(response => {
puter.print(response);
});
</script>
</body>
</html>
Example 2: Streaming with Reasoning
Step 3.5 Flash supports streaming responses with reasoning capabilities, allowing you to see the model's thought process in real-time.
<html>
<body>
<script src="https://js.puter.com/v2/"></script>
<script>
puter.ai
.chat(
"A farmer has 17 sheep. All but 9 run away. How many sheep does the farmer have left? Explain your reasoning step by step.",
{ model: "stepfun/step-3.5-flash:free", stream: true }
)
.then(async (resp) => {
for await (const part of resp) {
if (part?.reasoning) puter.print(part?.reasoning);
else puter.print(part?.text);
}
});
</script>
</body>
</html>
List of StepFun models
You can use the following StepFun models with Puter.js:
stepfun/step-3.5-flash:free
Conclusion
Using Puter.js, you can gain access to StepFun Step 3.5 Flash, a powerful reasoning model with ultra-fast inference speeds up to 350 tokens per second and 256K context length. Thanks to the User-Pays model, your users cover their own AI usage, not you as the developer. This means you can build powerful agentic applications without worrying about AI usage costs.
You can find all AI features supported by Puter.js in the documentation.
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