Anthropic: Claude Opus 4.1
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Claude Opus 4.1 is an August 2025 incremental upgrade to Opus 4 focused on agentic tasks and real-world coding. It improved coding accuracy to 74.5% on SWE-bench with finer-grained refactoring and more precise bug fixes.
Context Window 200K
tokens
Max Output 32K
tokens
Input Cost $15
per million tokens
Output Cost $75
per million tokens
Input text, image, pdf
modalities
Tool Use Yes
Knowledge Cutoff Mar 31, 2025
Release Date Aug 5, 2025
Code Example
Add AI to your app with the Puter.js AI API — no API keys or setup required.
// npm install @heyputer/puter.js
import { puter } from '@heyputer/puter.js';
puter.ai.chat("Explain quantum computing in simple terms").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").then(response => {
document.body.innerHTML = response.message.content;
});
</script>
</body>
</html>
More AI Models From Anthropic
Claude Fable 5.1
Claude Fable 5.1 is Anthropic's successor to Claude Fable 5, released September 1, 2026, about three months after Fable 5. Anthropic also released a companion model, Claude Mythos 5.1, available only through trusted access programs; both share the same underlying model with different safety safeguards. On SWE-bench Pro it scores 81.2%, ahead of Fable 5's 80% and Mythos 5's 80.3%. On Terminal-Bench-Science, a scientific-research agentic benchmark, it reaches 52.6%, more than double Fable 5's 24.7% and ahead of GPT-5.6 Sol's 22.4%. On Terminal-Bench 4.0 for agentic coding it scores 55.8%, versus 42.0% for Fable 5 and 37.3% for GPT-5.6 Sol. Priced at $10/$50 per million input/output tokens, unchanged from Fable 5, with cache reads cut 75% to $0.25 per million tokens. It offers a 1,000,000-token context window, 128,000-token max output, and tool calling. It fits developers running long-horizon agentic coding and research pipelines who want Fable-tier reasoning at lower cost.
ChatClaude Opus 5
Claude Opus 5 is Anthropic's flagship model, released July 24, 2026 as the successor to Claude Opus 4.8. Anthropic positions it as approaching the performance of its higher-tier Claude Fable 5 model at roughly half the token cost, built for agentic coding, computer use, and long-horizon knowledge work. On the ARC-AGI-3 novel problem-solving benchmark, Opus 5 scores 30.2%, roughly four times GPT-5.6 Sol's 7.8% and twenty times Opus 4.8's 1.5%. On the GDPval-AA v2 knowledge-work benchmark, it reaches an Elo of 1,861, ahead of Fable 5 (1,747) and GPT-5.6 Sol (1,736). Priced at $5 per million input tokens and $25 per million output tokens, unchanged from Opus 4.8, it offers a 1,000,000-token context window, 128,000-token max output, and tool calling. It fits developers building coding agents and automation pipelines that need strong reasoning at Opus-level pricing.
ChatClaude Opus 5 Fast
Claude Opus 5 Fast is a high-speed configuration of Anthropic's Opus 5 flagship model, generating output tokens at roughly 2.5x the speed of standard Opus 5. It runs the same Opus 5 model, which Anthropic says outperforms Opus 4.8 on agentic coding, computer use, and knowledge work, and approaches Fable 5's performance at roughly half the cost. Fast mode pricing is $10/$50 per million input/output tokens, twice the price of standard Opus 5 ($5/$25) and in line with what Opus 4.8 Fast cost. It supports the full 1M token context window and 128k max output tokens. Choose Opus 5 Fast for latency-sensitive agentic pipelines, live coding sessions, and real-time workflows where throughput matters. For cost-sensitive or batch workloads, standard Opus 5 offers the same intelligence at half the price.
Frequently Asked Questions
You can access Claude Opus 4.1 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 Opus 4.1 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 | $15 |
| Output | $75 |
Claude Opus 4.1 was created by Anthropic and released on Aug 5, 2025.
Claude Opus 4.1 supports a context window of 200K tokens. For reference, that is roughly equivalent to 400 pages of text.
Claude Opus 4.1 can generate up to 32K tokens in a single response.
Claude Opus 4.1 has a knowledge cutoff date of Mar 31, 2025. This means the model was trained on data available up to that date.
Claude Opus 4.1 accepts the following input types: text, image, pdf. It produces: text.
Yes, Claude Opus 4.1 supports tool use (function calling), allowing it to interact with external tools, APIs, and data sources as part of its response flow.
Claude Opus 4.1 scores 28.8 on the Artificial Analysis Intelligence Index, outperforming 67% of tracked models.
Yes — the Claude Opus 4.1 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.
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