Claude Opus 4.8: Release Date, Model ID and Availability

Last updated: July 18, 2026 · Release status, model ID, availability, pricing, context window and migration guidance checked against official Anthropic sources.

Is Claude Opus 4.8 released? Current status

Yes. Anthropic launched Claude Opus 4.8 on May 28, 2026. Its current models overview still lists claude-opus-4-8, so this is a released model rather than a roadmap name, leak or unconfirmed future version.

Claude Opus 4.8 release date, availability and API model ID

The official Claude Opus 4.8 release date is May 28, 2026. Anthropic’s launch announcement said the model was available immediately and gave developers the API identifier claude-opus-4-8. The current platform documentation lists the same identifier for the Claude API, with provider-specific identifiers documented separately for Amazon Bedrock and Google Cloud.

Anthropic describes the dateless claude-opus-4-8 name as a pinned model snapshot, not an evergreen alias that silently moves to a future Opus release. That matters for production evaluation: a test against this model ID remains tied to Opus 4.8 rather than automatically becoming a later model.

What changed in Claude Opus 4.8?

Opus 4.8 builds on Opus 4.7 rather than introducing a new API family. Anthropic’s current documentation highlights better long-horizon agentic coding, tool triggering, compaction recovery and effort calibration, plus several concrete platform changes.

Dynamic workflows are now generally available

Dynamic workflows let Claude Code plan a large task, dispatch tens to hundreds of parallel subagents, verify their work and return one coordinated result. The feature launched as a research preview with Opus 4.8, but Anthropic’s current product page now says it is generally available in Claude Code CLI, Desktop and the VS Code extension for Pro, Max, Team and Enterprise plans, as well as on supported API and cloud surfaces.

This is useful for decomposable work such as codebase-wide audits, migrations and independent verification. It is not a free performance multiplier: Anthropic warns that workflows can consume substantially more tokens than a typical Claude Code session. Start with a scoped task and measure usage before making workflows a default.

For a broader explanation of the orchestration pattern, see our agentic workflows guide.

Mid-conversation system messages

Opus 4.8 accepts a role: "system" message immediately after a user turn in the Messages API, subject to Anthropic’s placement rules. This lets an application update instructions during a long-running conversation without rebuilding the full history, which can preserve prompt-cache hits. The top-level system field remains the correct place for instructions that apply from the beginning.

Effort defaults and adaptive thinking

The effort parameter defaults to high across Opus 4.8 surfaces. Adaptive thinking is supported, but API requests without a thinking field run without thinking. Enable it with {"type":"adaptive"} and set depth through output_config.effort. Manual extended-thinking budgets are not supported on Opus 4.8.

Fast mode remains a research preview

Fast mode uses the same Opus 4.8 model with up to 2.5× higher output tokens per second. It is not a different or more capable model, and the benefit targets output speed rather than time to first token. As of the verification date it is an access-controlled research preview on the Claude API, not a generally available cloud-platform feature.

Lower cache minimum and documented refusal details

The minimum cacheable prompt length is 1,024 tokens, down from 2,048 on Opus 4.7. Anthropic also documents the stop_details object on refusals, which helps applications route different refusal categories without treating them as generic failures.

Claude Opus 4.8 pricing, context window and Fast mode

The official model overview lists a 1M-token context window and 128K maximum output for Opus 4.8 on the synchronous Messages API. The 1M window is included at standard per-token pricing. Provider-specific endpoint limits and identifiers can differ, so check the current platform documentation before assuming identical behavior across every cloud.

Fast mode is exactly 2× the standard input and output price. Because it accelerates output token generation rather than model intelligence, use it only where response speed has measurable product value. Requests at fast and standard speeds do not share prompt-cache prefixes, and a fast-mode rate or capacity error does not silently fall back to standard speed.

Claude Opus 4.8 benchmarks: what the results do and do not show

Anthropic’s launch materials report improvements across coding, agentic work, reasoning and practical knowledge tasks. These results are useful release signals, but most are vendor-run or partner-reported. They should guide what to test in your own harness, not replace workload-specific evaluation.

How to migrate from Opus 4.7 to Opus 4.8

Anthropic documents no breaking API changes for code already running on Opus 4.7. The required change is the model name; the main operational work is re-baselining behavior, latency and cost at your chosen effort setting.

from anthropic import Anthropic

client = Anthropic()

response = client.messages.create(
    model="claude-opus-4-8",       # was claude-opus-4-7
    max_tokens=16000,
    thinking={"type": "adaptive"},
    output_config={"effort": "high"},
    messages=[
        {"role": "user", "content": "Review this migration plan."}
    ],
)

Before moving production traffic:

• Swap the model ID from claude-opus-4-7 to claude-opus-4-8.
• Re-run your evals. Anthropic expects strong out-of-the-box performance on Opus 4.7 prompts, but behavior and effort calibration changed.
• Re-baseline latency and cost. The default effort level is high; set it explicitly if your product depends on a stable trade-off.
• Remove obsolete thinking configuration. Use adaptive thinking and output_config.effort, not budget_tokens.
• Remove an old long-context beta header if your Opus 4.7 client still sends one; the 1M window is now the default on supported endpoints.
• Handle refusal details and verify that downstream parsers tolerate the model’s updated response behavior.

For a practical coding-tool next step, compare Claude Code with Cursor.

Where Opus 4.8 fits in the current Claude model lineup

Opus 4.8 is the current Opus-tier model for complex agentic coding and enterprise work. It is a stable production choice when you specifically need the Opus balance of long-horizon execution, tool use and 1M context. It should not be described as Anthropic’s newest model across every tier, because the wider Claude lineup evolves independently.

Choose by workload rather than model name alone:

• Use Opus 4.8 when complex agentic coding, long tool chains and high-stakes knowledge work justify its cost.
• Use a cheaper current Claude tier when latency and unit economics matter more than maximum Opus capability.
• Use the current Claude model lineup for family-wide availability and price comparisons.
• Use the dedicated Claude Mythos status guide for restricted-model context rather than treating a May launch forecast as current Opus information.

Update log

• July 18, 2026: Rebuilt the page around release status, model ID and availability. Reverified pricing, context, maximum output and migration guidance; corrected adaptive-thinking code; updated dynamic workflows from research preview to generally available; removed stale Mythos timing and dated competitor rankings.
• June 2, 2026: Original release-week analysis published after the May 28 launch.