Claude Sonnet 4 API

Access Claude Sonnet 4 from Anthropic using Puter.js AI API.

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Model Card

Claude Sonnet 4 is the May 2025 successor to Sonnet 3.7 with enhanced steerability and coding (72.7% SWE-bench). It excels at following complex instructions precisely and autonomous multi-feature app development with near-zero navigation errors.

Context Window 200K

tokens

Max Output 64K

tokens

Input Cost $3

per million tokens

Output Cost $15

per million tokens

Input text, image, pdf

modalities

Tool Use Yes

 

Knowledge Cutoff Mar 31, 2025

 

Release Date May 22, 2025

 

API Usage Example

Add Claude Sonnet 4 to your app with just a few lines of code.
No API keys, no backend, no configuration required.

// npm install @heyputer/puter.js
import { puter } from '@heyputer/puter.js';

puter.ai.chat("Explain quantum computing in simple terms", {
    model: "anthropic/claude-sonnet-4"
}).then(response => {
    document.body.innerHTML = response.message.content;
});

<html>
<body>
    <script src="https://js.puter.com/v2/"></script>
    <script>
        puter.ai.chat("Explain quantum computing in simple terms", {
            model: "anthropic/claude-sonnet-4"
        }).then(response => {
            document.body.innerHTML = response.message.content;
        });
    </script>
</body>
</html>

View full documentation →

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Frequently Asked Questions

What is this Claude Sonnet 4 API about?

The Claude Sonnet 4 API gives you access to Anthropic's chat model through Puter.js. With just a few lines of JavaScript, you can integrate Claude Sonnet 4 into any web app or Node.js project — no API keys, no backend, and no configuration required.

Who created Claude Sonnet 4?

Claude Sonnet 4 was created by Anthropic and released on May 22, 2025.

What is the context window of Claude Sonnet 4?

Claude Sonnet 4 supports a context window of 200K tokens. For reference, that is roughly equivalent to 400 pages of text.

What is the max output length of Claude Sonnet 4?

Claude Sonnet 4 can generate up to 64K tokens in a single response.

What is the knowledge cutoff of Claude Sonnet 4?

Claude Sonnet 4 has a knowledge cutoff date of Mar 31, 2025. This means the model was trained on data available up to that date.

What types of input can Claude Sonnet 4 process?

Claude Sonnet 4 accepts the following input types: text, image, pdf. It produces: text.

Does Claude Sonnet 4 support tool use (function calling)?

Yes, Claude Sonnet 4 supports tool use (function calling), allowing it to interact with external tools, APIs, and data sources as part of its response flow.

How much does it cost?
The Claude Sonnet 4 API is available through the User-Pays Model. As a developer, you can add the Claude Sonnet 4 API to your app for free — your users pay for their own AI costs directly.
Price per 1M tokens
Input$3
Output$15
How do I access the Claude Sonnet 4 API?

You can access the Claude Sonnet 4 API with just a few lines of JavaScript — no API keys, no backend, and no configuration required. Include the Puter.js library in your project and start making calls right away. For more details, check out our documentation.

Does the Claude Sonnet 4 API work with React / Vue / Vanilla JS / Node / etc.?

Yes — the Claude Sonnet 4 API works with any JavaScript framework, Node.js, or plain HTML through Puter.js. Just include the library and start building. See the documentation for more details.

Get started with Puter.js

Add Claude Sonnet 4 to your app without worrying about API keys or setup.

Read the Docs View Tutorials