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 44
tokens / sec
Latency 1.37s
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 4.8
Claude Opus 4.8 is Anthropic's latest flagship AI model, building on Opus 4.7 with improvements across coding, reasoning, and knowledge work — at the same price point. The model excels at complex, multi-step agentic workflows including coding, financial analysis, legal reasoning, and browser-based computer use. Early testers report it outperforms both prior Opus models and GPT-5.5 across several agentic benchmarks. Notably, it's around four times less likely than Opus 4.7 to let flaws in generated code pass without flagging them. Opus 4.8 supports configurable effort levels, letting developers trade quality against speed and token cost. A fast mode operates at 2.5× speed. Priced at $5/$25 per million input/output tokens, it targets teams running autonomous agents, analysis pipelines, and long-running async workflows where reliability and judgment are critical.
ChatClaude Opus 4.8 Fast
Claude Opus 4.8 Fast is a high-speed configuration of Anthropic's latest flagship model, delivering up to 2.5x faster output token generation at significantly lower cost than previous fast variants. It runs the same Opus 4.8 model — which improves on Opus 4.7 in agentic coding (69.2% vs 64.3%), multidisciplinary reasoning with tools (57.9% vs 54.7%), and knowledge work — but optimized for lower latency. Fast mode pricing is $10/$50 per million input/output tokens, three times cheaper than fast mode for Opus 4.6 and 4.7 ($30/$150). It supports the full 1M token context window and 128k max output tokens. Choose Opus 4.8 Fast for latency-sensitive agentic pipelines, live coding sessions, and real-time workflows where throughput matters. For cost-sensitive or batch workloads, standard Opus 4.8 offers the same intelligence at half the price.
ChatClaude Opus 4.7 Fast
Claude Opus 4.7 Fast is a high-speed configuration of Anthropic's most capable model, delivering up to 2.5x faster output token generation with no reduction in quality or capabilities. It runs the same Opus 4.7 model — which scores 87.6% on SWE-bench Verified (up from 80.8% on Opus 4.6), 94.2% on GPQA Diamond, and 69.4% on Terminal-Bench 2.0 — 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 benefits are focused on output tokens per second, not time to first token. It is ideal for latency-sensitive agentic workflows, live coding sessions, and real-time tasks where response speed matters. For cost-sensitive or batch workloads, standard Opus 4.7 offers the same intelligence at lower cost.
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.
Claude Sonnet 4.5 scores 37.1 on the Artificial Analysis Intelligence Index, outperforming 78% of tracked models. On coding, it scores 33.5 (outperforms 75% of models). On math, it scores 37.0 (outperforms 37% of models).
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.
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