Anthropic: Claude Opus 4.8
anthropic/claude-opus-4-8
Access Claude Opus 4.8 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-opus-4-8"
}).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-opus-4-8"
}).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-opus-4-8",
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-opus-4-8",
"messages": [
{"role": "user", "content": "Explain quantum computing in simple terms"}
]
}'
Model Card
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.
Context Window 1M
tokens
Max Output 128K
tokens
Input Cost $5
per million tokens
Output Cost $25
per million tokens
Input text, image, pdf
modalities
Tool Use Yes
Knowledge Cutoff Jan 2026
Release Date May 28, 2026
Model Playground
Try Claude Opus 4.8 instantly in your browser.
This playground uses the Puter.js AI API — no API keys or setup required.
Benchmarks
How Claude Opus 4.8 performs on standard evaluations.
| Benchmark | Score |
|---|---|
| GPQA Diamond Graduate-level science Q&A | 92.0% |
| Humanity's Last Exam Cross-domain reasoning | 48.7% |
| SciCode Scientific programming | 54.4% |
| IFBench Instruction following | 62.2% |
| LCR Long-context reasoning | 77.7% |
| Terminal-Bench Hard Agentic terminal tasks | 58.3% |
| τ²-Bench Tool use / agents | 94.4% |
Scores sourced from Artificial Analysis.
Find other Anthropic models →
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 4.8 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 4.8 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 | $5 |
| Output | $25 |
Claude Opus 4.8 was created by Anthropic and released on May 28, 2026.
Claude Opus 4.8 supports a context window of 1M tokens. For reference, that is roughly equivalent to 2,000 pages of text.
Claude Opus 4.8 can generate up to 128K tokens in a single response.
Claude Opus 4.8 has a knowledge cutoff date of Jan 2026. This means the model was trained on data available up to that date.
Claude Opus 4.8 accepts the following input types: text, image, pdf. It produces: text.
Yes, Claude Opus 4.8 supports tool use (function calling), allowing it to interact with external tools, APIs, and data sources as part of its response flow.
Claude Opus 4.8 scores 46.4 on the Artificial Analysis Intelligence Index, outperforming 94% of tracked models. On coding, it scores 74.3 (outperforms 87% of models).
Yes — the Claude Opus 4.8 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 Opus 4.8 to your app without worrying about API keys or setup.
Read the Docs View Tutorials