What Is Claude Opus 4.8?
Anthropic released Claude Opus 4.8 on May 28, 2026. It is the latest and most advanced version of Anthropic's flagship AI model. Released less than 2 months after Opus 4.7 — showing a faster upgrade cadence.
“Stronger across coding, agentic tasks, and professional work, Opus 4.8 has the consistency and autonomy to keep working on long-running tasks.”
— Anthropic
Areas of Improvement:
- Agentic Coding
- Multidisciplinary Reasoning
- Agentic Computer Use
- Knowledge Work
- Agentic Financial Analysis
Model ID
claude-opus-4-8
Release Date
May 28, 2026
Developer
Anthropic
Predecessor
Opus 4.7 (Apr 16, 2026)
Price Change
NONE
Key Improvements Over Opus 4.7
01Honesty & Reliability
The most emphasized improvement in Opus 4.8 is honesty. AI models often jump to conclusions and claim progress without evidence. Opus 4.8 is trained to actively fight this problem.
Results
- 4x LESS likely to allow code flaws to go unremarked
- More likely to flag uncertainties in its own work
- Less likely to make unsupported or unverified claims
- More transparent when it lacks sufficient information
“Early testers report that Opus 4.8 is more likely to flag uncertainties about its work and less likely to make unsupported claims.”
— Anthropic
02Fast Mode — Speed & Cost
- Fast Mode now runs at 2.5x the speed of standard mode
- Fast Mode is now 3x CHEAPER than it was for previous Opus models
- This makes Opus 4.8 far more practical for high-frequency workloads
03Agentic Judgment
- Sharper judgment when performing long-running agentic tasks
- Asks the right questions before making big decisions
- Catches its own mistakes mid-task
- Pushes back when a plan isn't sound
- Works more autonomously over extended sessions
04Alignment & Safety
- Reaches new highs on prosocial traits: supporting user autonomy and acting in the user's best interest
- Deception and misuse rates substantially LOWER than Opus 4.7
- Alignment scores now COMPARABLE to Claude Mythos Preview (Anthropic's most advanced aligned model)
Benchmark Results
Claude Opus 4.8 Benchmark Performance
Head-to-head comparison against Opus 4.7 across key evaluations
vs Competitors
- Outperforms GPT-5.5 on: SWE-Bench Pro, Reasoning, Browser Agent
- Outperforms Gemini 3.1 on: Most benchmarks
- GPT-5.5 leads only on: Terminal-Bench (using Codex CLI harness 83.4%)
Notes
- Terminal-Bench tested using Terminus-2 public harness for Opus 4.8
- GPT-5.5 Terminal-Bench score (83.4%) uses Codex CLI harness (different)
- OSWorld-Verified methodology updated for real-world accuracy (Opus 4.7 score updated to 82.3% under new methodology)
New Features Launched with Opus 4.8
Dynamic Workflows — Claude Code
Research PreviewWhat it does:
- Claude plans the full work upfront
- Spawns HUNDREDS of parallel subagents in a single session
- Each subagent handles a small piece of the task
- Verifies all outputs before reporting back to user
- Handles massive codebase migrations end-to-end
Real Example
Claude Code + Opus 4.8 can rewrite an entire application in a new programming language — from kickoff to merge — using the existing test suite as its quality bar.
Dynamic Workflows — Claude Code
How Claude Code orchestrates massive parallel execution pipelines
Strategic Planning
Claude plans the full scope of work upfront — analyzing the codebase, decomposing the task, and mapping dependencies before a single line is touched.
Parallel Subagents
Hundreds of parallel subagents are spawned simultaneously, each assigned a discrete chunk of the work graph. This is massively concurrent execution.
Distributed Execution
Each subagent independently handles its piece — editing files, running tests, validating outputs. No bottleneck. No sequential wait.
Automated Verification
All outputs are verified against acceptance criteria. Tests pass, lint passes, type-checks pass. Nothing ships without proof.
Merged Output
Final merged output delivered as a cohesive, clean result. Thousands of changes, one unified delivery. Production-ready.
Effort Control — claude.ai & Cowork
LiveEffort Control Levels
Dial Claude's computational intensity to match your task complexity
Simple queries, fast replies
For straightforward tasks that need quick answers. Claude responds instantly with minimal computation, keeping latency ultra-low and costs down.
Default — general tasks
The default mode for most development tasks. Claude thinks carefully, considers context, and delivers thoughtful, accurate responses across a wide range of complexity.
Difficult tasks, async workflows
For challenging tasks that benefit from extended reasoning. Claude takes more time to explore solution spaces, consider edge cases, and produce higher-quality outputs.
Hardest tasks, maximum performance
Full computational power unlocked. Claude uses maximum extended thinking, exploring all possible approaches. Reserved for the most demanding engineering challenges.
Notes:
- Higher effort = thinks more deeply = better results
- Lower effort = faster response = slower rate limit usage
- Rate limits increased in Claude Code for extra/max levels
Mid-Task System Prompts — Messages API
LiveWhat it does:
- System entries can now be passed INSIDE the messages array
- Update Claude's instructions mid-task without breaking the prompt cache or routing through a user turn
Use cases:
- Update permissions mid-agent run
- Update token budgets dynamically
- Update environment context as agent progresses
Increased Rate Limits — Claude Code
Live- Rate limits raised to support extra and max effort token usage
- Users can select effort level that fits their project needs
Early Tester Feedback
“Claude Opus 4.8 has noticeably better judgment. In Claude Code, it asks the right questions, catches its own mistakes, pushes back when a plan isn't sound.”
Tom Pritchard— Staff Engineer
“On our Super-Agent benchmark, Claude Opus 4.8 is the only model to complete every case end-to-end, beating prior Opus models and GPT-5.5 at parity on cost.”
Kay Zhu— Co-Founder and CTO
“On CursorBench, Claude Opus 4.8 exceeds prior Opus models across every effort level. Tool calling is meaningfully more efficient, using fewer steps for the same intelligence.”
Michael Truell— Co-Founder & CEO, Cursor
“Claude Opus 4.8 delivers the highest score on our Legal Agent Benchmark and is the first model to break 10% on the all-pass standard.”
Niko Grupen— Head of Applied Research
“Claude Opus 4.8 is the strongest computer-use and browser-agent model we've tested, scoring 84% on Online-Mind2Web — a meaningful jump over both Opus 4.7 and GPT-5.5.”
Miguel Gonzalez— Tech Lead
“It improves on Opus 4.6 and fixes the comment-verbosity and tool-calling issues we saw with Opus 4.7. This translates directly into faster capability gains for engineers building on Devin.”
Scott Wu— CEO, Devin
“Its multimodal strength lets Genie reason over PDFs, diagrams, and unstructured content at 61% cheaper token cost than Opus 4.7.”
Hanlin Tang— CTO Neural Networks, Databricks
“The biggest differentiator was Opus 4.8's tendency to proactively flag issues — something other models routinely missed and left to users to catch.”
Michael Ran— Sr. Investment Associate
“Across CoCounsel Legal, Claude Opus 4.8 delivered meaningful improvements in consistency and reasoning quality. For high-stakes professional workflows, that reliability matters.”
Joel Hron— CTO, CoCounsel
“Claude Opus 4.8 feels like a major quality-of-life update over Opus 4.7: faster, easier to collaborate with, and better at carrying context across a long session.”
Katie Parrott— Staff Writer
Pricing
Unchanged from Opus 4.7:
| Mode & Direction | Price per 1M Tokens |
|---|---|
| Standard — Input | $5.00 |
| Standard — Output | $25.00 |
| Fast Mode — Input | $10.00 |
| Fast Mode — Output | $50.00 |
Key Points
- Zero price increase from Opus 4.7
- Fast mode is 3x CHEAPER than previous Opus fast mode pricing
- Fast mode runs 2.5x FASTER than standard mode
- Available: claude.ai, API, Vertex AI, AWS Bedrock, MS Foundry
API Access & Code
Model ID: claude-opus-4-8
import anthropic
client = anthropic.Anthropic(api_key="YOUR_API_KEY")
message = client.messages.create(
model="claude-opus-4-8",
max_tokens=8192,
messages=[
{"role": "user", "content": "Your prompt here"}
]
)
print(message.content)const response = await fetch("https://api.anthropic.com/v1/messages", {
method: "POST",
headers: {
"x-api-key": "YOUR_API_KEY",
"anthropic-version": "2023-06-01",
"content-type": "application/json"
},
body: JSON.stringify({
model: "claude-opus-4-8",
max_tokens: 8192,
messages: [
{ role: "user", content: "Your prompt here" }
]
})
});
const data = await response.json();
console.log(data.content);curl https://api.anthropic.com/v1/messages \
-H "x-api-key: YOUR_API_KEY" \
-H "anthropic-version: 2023-06-01" \
-H "content-type: application/json" \
-d '{
"model": "claude-opus-4-8",
"max_tokens": 8192,
"messages": [
{"role": "user", "content": "Your prompt here"}
]
}'Available Via
Anthropic API
platform.claude.com
Google Cloud
Vertex AI Model Garden
Amazon
AWS Bedrock
Microsoft
Azure AI Foundry
Opus Model Timeline
Opus 4.8
Honesty focus, Dynamic Workflows, 2.5x fast mode, 4x better code review
Opus 4.7
Stronger coding, vision, complex multi-step tasks
Opus 4.6
Reliability & precision for enterprise agents and workflows
Opus 4.5
Foundation of the Opus 4.x series
What's Coming Next
Claude Mythos — Next Generation Model Class
- Intelligence level: HIGHER than Opus
- Currently: Testing with small number of organizations — Cybersecurity focus (Project Glasswing)
- Requires stronger cyber safeguards before public release
- ETA: “Coming weeks” for all customers
- Opus 4.8 alignment is already at Mythos Preview level
“We plan to release a new class of model with even higher intelligence than Opus. We expect to bring Mythos-class models to all customers in the coming weeks.”
— Anthropic
Also Coming: Models with same Opus capabilities at a LOWER COST (Smarter Sonnet or new affordable tier — not confirmed yet).
$65 Billion Funding Round
$65B
Series H Raised
$965B
Valuation
Largest AI round in history
As of May 2026
Complete Quick Reference
| Property | Value |
|---|---|
| Model Name | Claude Opus 4.8 |
| API Model ID | claude-opus-4-8 |
| Release Date | May 28, 2026 |
| Developer | Anthropic |
| Predecessor | Claude Opus 4.7 (Apr 16, 2026) |
| SWE-Bench Pro | 69.2% (+4.9% vs 4.7) |
| Terminal-Bench 2.1 | 74.2% (+8.4% vs 4.7) |
| Multidisciplinary Reasoning | 57.9% (+3.2% vs 4.7) |
| Online-Mind2Web (Browser) | 84% — Best in class |
| Legal Agent Benchmark | Highest recorded — First 10% all-pass |
| Code Flaw Detection | 4x less likely to miss flaws |
| Standard Input Price | $5 per 1M tokens |
| Standard Output Price | $25 per 1M tokens |
| Fast Mode Input Price | $10 per 1M tokens |
| Fast Mode Output Price | $50 per 1M tokens |
| Price Change vs 4.7 | NONE |
| Fast Mode Speed | 2.5x faster than standard |
| Fast Mode Cost Change | 3x cheaper than previous fast mode |
| New Feature 1 (Claude Code) | Dynamic Workflows (Research Preview) |
| Dynamic Workflows Plans | Enterprise, Team, Max |
| New Feature 2 (claude.ai) | Effort Control (All plans) |
| Effort Levels | Low / High (default) / Extra / Max |
| Claude Code Effort IDs | low / high / xhigh / max |
| New Feature 3 (API) | Mid-task system prompt updates |
| New Feature 4 (Claude Code) | Increased rate limits |
| Alignment Level | Comparable to Claude Mythos Preview |
| Prosocial Traits | New highs vs all previous Opus models |
| Deception Rate | Substantially lower than Opus 4.7 |
| Coming Next | Mythos-class models (weeks away) |
| Funding Raised | $65 Billion (Series H) |
| Anthropic Valuation | $965 Billion |
Sources
All data sourced from Anthropic's official release — May 28, 2026
Frequently Asked Questions
Claude Opus 4.8 is Anthropic's latest and most advanced flagship AI model, released on May 28, 2026. It is stronger across coding, agentic tasks, and professional work, with the consistency and autonomy to keep working on long-running tasks.
Opus 4.8 scores 69.2% on SWE-Bench Pro (+4.9%), 74.2% on Terminal-Bench 2.1 (+8.4%), and 57.9% on Multidisciplinary Reasoning (+3.2%). It is also 4x less likely to allow code flaws to go unremarked, and features a 2.5x faster Fast Mode that is 3x cheaper than previous Opus fast mode pricing.
Dynamic Workflows is a Research Preview feature in Claude Code where Claude plans the full work upfront, spawns hundreds of parallel subagents in a single session, each handling a small piece of the task, verifies all outputs before reporting back, and can handle massive codebase migrations end-to-end.
Effort Control lets users choose how deeply Claude thinks — from Low (simple queries, fast replies) to High (default, general tasks), Extra (difficult tasks, async workflows), and Max (hardest tasks, maximum performance). Higher effort means deeper thinking and better results.
Claude Opus 4.8 pricing is unchanged from Opus 4.7: Standard Input at $5 per 1M tokens, Standard Output at $25 per 1M tokens, Fast Mode Input at $10 per 1M tokens, and Fast Mode Output at $50 per 1M tokens. Zero price increase from the previous version.
Claude Mythos is Anthropic's upcoming next-generation model class with intelligence higher than Opus. It is currently being tested with a small number of organizations focused on cybersecurity (Project Glasswing), and Anthropic expects to bring Mythos-class models to all customers in the coming weeks.
Yes, Claude Opus 4.8 outperforms GPT-5.5 on SWE-Bench Pro, Multidisciplinary Reasoning, and Online-Mind2Web (Browser Agent). GPT-5.5 leads only on Terminal-Bench when using its specialized Codex CLI harness (83.4%).
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