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Model

Claude Opus 4.8

Released on 28 May 2026 at the same price as Opus 4.7, Claude Opus 4.8 added a fast mode at 2.5 times the speed, with fewer unnoticed flaws in its own code. Anthropic called it a modest but tangible improvement.

Status AvailableModality Text, ImageContext (K tokens) 1000 Era Generative AI for everyone

License
Proprietary
Access
API, App, Enterprise
Release date
Developer
Anthropic

What it is

Claude Opus 4.8 is a large language model developed by Anthropic and released on 28 May 2026 under the API identifier claude-opus-4-8. Anthropic described it as a “modest but tangible improvement” on Opus 4.7, at the same $5 per million input tokens and $25 per million output tokens.[1]

Origins

Anthropic described Opus 4.8 as a step below Claude Mythos, and said Mythos-class models would reach all customers in the coming weeks.[1]

It later became the fallback model for Claude Fable 5. Requests in restricted areas such as cybersecurity, biology and chemistry are answered by Opus 4.8.[4]

According to Wikipedia, training data for the model ran to January 2026.[5]

Main features

Fast mode runs the model at 2.5 times its normal speed for $10 per million input tokens and $50 per million output tokens. Anthropic said this was three times cheaper than fast mode had been before. Anthropic's pricing documentation lists fast mode for Opus 4.8 as a research preview.[1][2]

The model scored 84% on Online-Mind2Web, a benchmark of web browsing tasks. A tester reported that it was the first model to break 10% overall on the all-pass standard of a legal agent benchmark, meaning a task counted only when every part of it was completed.[1]

Anthropic said the model was about four times less likely than Opus 4.7 to let flaws in its own code pass unremarked, and more likely to flag uncertainty.[1]

Its misaligned-behaviour rates were substantially lower than Opus 4.7's and similar to those of Claude Mythos Preview.[1]

The release launched dynamic workflows in Claude Code, in research preview. These plan work and run hundreds of parallel subagents, which are smaller model instances that handle parts of a task. An effort selector also arrived in claude.ai and Cowork on all plans.[1]

The Messages API began accepting system entries inside the messages array. Instructions can therefore change partway through a task without breaking the prompt cache, the stored prefix that lets repeated requests run faster and cheaper.[1]

Its place in development

Anthropic recommends Opus 4.8 as the replacement for retired Claude Opus 4, Opus 4.1 and Opus 3. Its retirement is not sooner than 28 May 2027.[3]

CapabilitiesLarge language modelsCodeAgents & tool use

Governance & standardsSafety & governance

Version history

20
  1. 2023
    • Mar 14, 2023 Claude (March 2023)

      Claude is the AI assistant Anthropic announced on 14 March 2023, its first publicly available assistant. It was built around training AI to be helpful, honest and harmless, and it started the Claude model line.

    • Jul 11, 2023 Claude 2

      Claude 2 is the second major version of Anthropic's assistant model, released on 11 July 2023 with better performance and longer responses. It was the first Claude model open to the general public.

    • Nov 21, 2023 Claude 2.1

      Claude 2.1, released on 21 November 2023, doubled the context window to 200,000 tokens and cut false statements by half compared with Claude 2.0. It added tool use and system prompts.

  2. 2024
    • Mar 4, 2024 Claude 3 Opus

      Claude 3 Opus, announced on 4 March 2024, was the most capable model in the Claude 3 family. It added vision and launched with a 200K-token context window and a Needle In A Haystack recall above 99%.

    • Mar 4, 2024 Claude 3 Sonnet

      Claude 3 Sonnet was the middle model of Anthropic's Claude 3 family, announced on 4 March 2024. It powered the free tier of claude.ai, offered a 200K-token context window, and was retired on 21 July 2025.

    • Jun 20, 2024 Claude 3.5 Sonnet

      Claude 3.5 Sonnet, released on 20 June 2024, was the first model of the Claude 3.5 family. It ran twice as fast as Claude 3 Opus at the mid-tier price and powered the new Artifacts and Projects features.

    • Oct 22, 2024 Claude 3.5 Sonnet (October 2024 upgrade)

      The upgraded Claude 3.5 Sonnet, announced on 22 October 2024, raised coding and agentic scores and introduced computer use in public beta, the first such offer from a frontier AI model.

  3. 2025
    • Feb 24, 2025 Claude 3.7 Sonnet

      Claude 3.7 Sonnet, released on 24 February 2025, was described by Anthropic as the first hybrid reasoning model on the market, able to answer quickly or think step by step at length. It launched with Claude Code.

    • May 22, 2025 Claude 4 (Claude Opus 4 and Claude Sonnet 4)

      Claude Opus 4 and Claude Sonnet 4, announced on 22 May 2025, were hybrid models with extended thinking. Anthropic called Opus 4 the best coding model in the world, and Claude Code became generally available the same day.

    • Aug 5, 2025 Claude Opus 4.1

      Claude Opus 4.1, released on 5 August 2025, upgraded Claude Opus 4 for agentic tasks, real-world coding and reasoning, at the same price. Anthropic later succeeded it with Claude Opus 4.5.

    • Sep 29, 2025 Claude Sonnet 4.5

      Claude Sonnet 4.5, released on 29 September 2025, was a drop-in replacement for Sonnet 4 at the same price. Anthropic reported that it could stay focused on complex tasks for more than 30 hours.

    • Nov 24, 2025 Claude Opus 4.5

      Claude Opus 4.5, released on 24 November 2025, cost a third as much as Opus 4.1 per token and introduced an effort parameter that lets developers trade capability for time and cost. Claude Opus 4.6 succeeded it.

  4. 2026
    • Feb 5, 2026 Claude Opus 4.6

      Released on 5 February 2026, Claude Opus 4.6 was an upgrade to Anthropic's smartest model. It was the first Opus-class model with a 1M-token context window, in beta at launch, and it introduced agent teams in Claude Code.

    • Feb 17, 2026 Claude Sonnet 4.6

      Released on 17 February 2026 with a 1M-token context window in beta, Claude Sonnet 4.6 kept the price of Sonnet 4.5 and became the default model for Free and Pro users on claude.ai.

    • Apr 16, 2026 Claude Opus 4.7

      Released on 16 April 2026 at the same price as Opus 4.6, Claude Opus 4.7 added an xhigh effort level and accepted much larger images. It was the first model to test automatic blocking of high-risk cybersecurity requests.

    • May 28, 2026 Claude Opus 4.8 · This page

      Released on 28 May 2026 at the same price as Opus 4.7, Claude Opus 4.8 added a fast mode at 2.5 times the speed, with fewer unnoticed flaws in its own code. Anthropic called it a modest but tangible improvement.

    • Jun 30, 2026 Claude Sonnet 5

      Claude Sonnet 5, released on 30 June 2026, is Anthropic's most agentic Sonnet model. It can make plans, use browsers and terminals, and run autonomously, at an introductory price of $2 and $10 per million tokens.

    • Jul 24, 2026 Claude Opus 5

      Claude Opus 5, released on 24 July 2026 at $5 and $25 per million tokens, is Anthropic's most aligned model to date and its most capable generally available model for scientific research.

    • Sep 22, 2026 Claude Opus 5.5

      Claude Opus 5.5, released on 22 September 2026, is the first model in Anthropic's Claude 5.5 family. Anthropic said it performs at the level of Fable 5.1 on most work, at about 40% lower cost than Opus 5.

    • Sep 28, 2026 Claude Sonnet 5.5

      Claude Sonnet 5.5, released on 28 September 2026, is the second model in the Claude 5.5 family and Anthropic's fastest Sonnet to date. It costs $2 and $10 per million tokens, with cache reads halved in October 2026.

20262

  1. ReleaseAnthropic releases Claude Fable 5 and Claude Mythos 5

    On 9 June 2026 Anthropic released Claude Fable 5, its first Mythos-class model for general use, and Claude Mythos 5, the same model with some safeguards lifted for vetted partners. Both were priced at $10 and $50 per million tokens.

  2. ReleaseAnthropic releases Claude Opus 4.8

    On 28 May 2026 Anthropic released Claude Opus 4.8, a modest improvement on Opus 4.7 at the same price. Fast mode became three times cheaper, and Claude Code gained dynamic workflows that run hundreds of parallel subagents.

Developed by1

Anthropic

Succeeded by1

Claude Opus 5

Successor of1

Claude Opus 4.7

Powers3

Claude apps (claude.ai)Claude CodeClaude Cowork

Uses3

Chain of thought and reasoning modelsTransformerConstitutional AI

Notes and sources

  1. Introducing Claude Opus 4.8https://www.anthropic.com/news/claude-opus-4-8
  2. Pricinghttps://platform.claude.com/docs/en/about-claude/pricing
  3. Model deprecationshttps://platform.claude.com/docs/en/about-claude/model-deprecations
  4. Claude Fable 5 and Claude Mythos 5https://www.anthropic.com/news/claude-fable-5-mythos-5
  5. Claude (language model)https://en.wikipedia.org/wiki/Claude_(language_model)

Cite this page: Claude Opus 4.8. TellWorld, https://www.tellworld.net/models/claude-opus-4-8. Updated 2026-11-08