Anthropic: Claude Sonnet 4.5
anthropic/claude-sonnet-4-5
Access Claude Sonnet 4.5 from Anthropic using Puter.js AI API.
Get Started// npm install @heyputer/puter.js
import { puter } from '@heyputer/puter.js';
puter.ai.chat("Explain quantum computing in simple terms", {
model: "anthropic/claude-sonnet-4-5"
}).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-4-5"
}).then(response => {
document.body.innerHTML = response.message.content;
});
</script>
</body>
</html>
# pip install openai
from openai import OpenAI
client = OpenAI(
base_url="https://api.puter.com/puterai/openai/v1/",
api_key="YOUR_PUTER_AUTH_TOKEN",
)
response = client.chat.completions.create(
model="anthropic/claude-sonnet-4-5",
messages=[
{"role": "user", "content": "Explain quantum computing in simple terms"}
],
)
print(response.choices[0].message.content)
curl https://api.puter.com/puterai/openai/v1/chat/completions \
-H "Content-Type: application/json" \
-H "Authorization: Bearer YOUR_PUTER_AUTH_TOKEN" \
-d '{
"model": "anthropic/claude-sonnet-4-5",
"messages": [
{"role": "user", "content": "Explain quantum computing in simple terms"}
]
}'
Model Card
Claude Sonnet 4.5 is Anthropic's most capable model for agents and computer use, released September 2025. It can maintain focus for 30+ hours on complex tasks, supports a 1M token context window (beta), and is described as their "most aligned frontier model."
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 Jul 31, 2025
Release Date Sep 29, 2025
Output Speed 53
tokens / sec
Latency 1.19s
time to first token
Model Playground
Try Claude Sonnet 4.5 instantly in your browser.
This playground uses the Puter.js AI API — no API keys or setup required.
Benchmarks
How Claude Sonnet 4.5 performs on standard evaluations.
| Benchmark | Score |
|---|---|
| GPQA Diamond Graduate-level science Q&A | 72.7% |
| Humanity's Last Exam Cross-domain reasoning | 7.1% |
| LiveCodeBench Recent coding problems | 59.0% |
| SciCode Scientific programming | 42.8% |
| AIME 2025 Advanced math exam | 37.0% |
| IFBench Instruction following | 42.7% |
| LCR Long-context reasoning | 51.3% |
| Terminal-Bench Hard Agentic terminal tasks | 28.8% |
| τ²-Bench Tool use / agents | 70.5% |
Scores sourced from Artificial Analysis.
Find other Anthropic models →
Claude Opus 4.7
Claude Opus 4.7 is Anthropic's most capable generally available model, built for complex reasoning and agentic coding. It offers a step-change improvement in long-horizon agentic work over its predecessor, Opus 4.6, along with strong gains in knowledge work, vision, and file-system-based memory. The model supports a 1M-token context window, 128k max output tokens, and adaptive thinking. It introduces high-resolution image input (up to 2576px / 3.75MP), a new `xhigh` effort level for demanding coding tasks, and task budgets (beta) that let the model self-moderate token usage across an agentic loop. Priced at $5 / $25 per million input/output tokens. Best suited for developers building autonomous agents, multi-step coding workflows, and vision-heavy pipelines where reliability and depth of reasoning matter most.
ChatClaude Opus 4.6 Fast
Claude Opus 4.6 Fast is a high-speed configuration of Anthropic's most intelligent model, delivering up to 2.5x faster output token generation with no reduction in quality or capabilities. It runs the same Opus 4.6 model — state-of-the-art on benchmarks like Terminal-Bench 2.0 for agentic coding, Humanity's Last Exam for multidisciplinary reasoning, and GDPval-AA for professional knowledge work — but optimized for lower latency at premium pricing ($30/$150 per MTok). It supports the full 1M token context window and 128k max output tokens. Fast mode is ideal for latency-sensitive, interactive workflows such as rapid iteration, live debugging, and real-time agentic tasks where waiting on responses breaks your flow. For cost-sensitive or batch workloads, standard Opus 4.6 offers the same intelligence at lower cost.
ChatClaude Sonnet 4.6
Claude Sonnet 4.6 is Anthropic's latest mid-tier model released February 2026, delivering near-flagship Opus-level performance in coding, computer use, and agentic tasks at a fraction of the cost ($3/$15 per million tokens). It features a 1M token context window in beta, scores 79.6% on SWE-bench Verified and 72.5% on OSWorld. Developers preferred it over both Sonnet 4.5 (~70% of the time) and even Opus 4.5 (~59%) in real-world coding tests.
Frequently Asked Questions
You can access Claude Sonnet 4.5 by Anthropic through Puter.js AI API. Include the library in your web app or Node.js project and start making calls with just a few lines of JavaScript — no backend and no configuration required. You can also use it with Python or cURL via Puter's OpenAI-compatible API.
Yes, it is free if you're using it through Puter.js. With the User-Pays Model, you can add Claude Sonnet 4.5 to your app at no cost — your users pay for their own AI usage directly, making it completely free for you as a developer.
| Price per 1M tokens | |
|---|---|
| Input | $3 |
| Output | $15 |
Claude Sonnet 4.5 was created by Anthropic and released on Sep 29, 2025.
Claude Sonnet 4.5 supports a context window of 200K tokens. For reference, that is roughly equivalent to 400 pages of text.
Claude Sonnet 4.5 can generate up to 64K tokens in a single response.
Claude Sonnet 4.5 has a knowledge cutoff date of Jul 31, 2025. This means the model was trained on data available up to that date.
Claude Sonnet 4.5 accepts the following input types: text, image, pdf. It produces: text.
Yes, Claude Sonnet 4.5 supports tool use (function calling), allowing it to interact with external tools, APIs, and data sources as part of its response flow.
Yes — the Claude Sonnet 4.5 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 4.5 to your app without worrying about API keys or setup.
Read the Docs View Tutorials