Anthropic Models

Claude Opus 4.1 is an updated version of Anthropic’s flagship model, offering improved performance in coding, reasoning, and agentic tasks. It achieves 74.5% on SWE-bench Verified and shows notable gains in multi-file code refactoring, debugging precision, and detail-oriented reasoning. The model supports extended thinking up to 64K tokens and is optimized for tasks involving research, data analysis, and tool-assisted reasoning.

Claude Sonnet 4.5 is Anthropic’s most advanced Sonnet model to date, optimized for real-world agents and coding workflows. It delivers state-of-the-art performance on coding benchmarks such as SWE-bench Verified, with improvements across system design, code security, and specification adherence. The model is designed for extended autonomous operation, maintaining task continuity across sessions and providing fact-based progress tracking.

Sonnet 4.5 also introduces stronger agentic capabilities, including improved tool orchestration, speculative parallel execution, and more efficient context and memory management. With enhanced context tracking and awareness of token usage across tool calls, it is particularly well-suited for multi-context and long-running workflows. Use cases span software engineering, cybersecurity, financial analysis, research agents, and other domains requiring sustained reasoning and tool use.

Claude Haiku 4.5 is Anthropic’s fastest and most efficient model, delivering near-frontier intelligence at a fraction of the cost and latency of larger Claude models. Matching Claude Sonnet 4’s performance across reasoning, coding, and computer-use tasks, Haiku 4.5 brings frontier-level capability to real-time and high-volume applications.

It introduces extended thinking to the Haiku line; enabling controllable reasoning depth, summarized or interleaved thought output, and tool-assisted workflows with full support for coding, bash, web search, and computer-use tools. Scoring >73% on SWE-bench Verified, Haiku 4.5 ranks among the world’s best coding models while maintaining exceptional responsiveness for sub-agents, parallelized execution, and scaled deployment.

Claude Opus 4.5 is Anthropic's latest frontier reasoning model, purpose-built for complex software engineering, agentic workflows, and long-horizon computer use. It delivers strong multimodal capabilities, competitive performance on real-world coding and reasoning benchmarks, and improved robustness against prompt injection attacks. The model is designed to operate efficiently across varied effort levels, allowing developers to balance speed, depth, and token usage based on their specific task requirements—you can fine-tune token efficiency through the OpenRouter Verbosity parameter, which offers low, medium, and high settings. Beyond that, Opus 4.5 supports advanced tool use, extended context management, and coordinated multi-agent setups, making it ideal for autonomous research, debugging, multi-step planning, and spreadsheet or browser manipulation. Compared to previous Opus generations, it brings substantial improvements in structured reasoning, execution reliability, and alignment, while reducing token overhead and delivering more consistent performance on long-running tasks.

Opus 4.6 is Anthropic’s strongest model for coding and long-running professional tasks. It is built for agents that operate across entire workflows rather than single prompts, making it especially effective for large codebases, complex refactors, and multi-step debugging that unfolds over time. The model shows deeper contextual understanding, stronger problem decomposition, and greater reliability on hard engineering tasks than prior generations.

Beyond coding, Opus 4.6 excels at sustained knowledge work. It produces near-production-ready documents, plans, and analyses in a single pass, and maintains coherence across very long outputs and extended sessions. This makes it a strong default for tasks that require persistence, judgment, and follow-through, such as technical design, migration planning, and end-to-end project execution.

For users upgrading from earlier Opus versions, see our official migration guide here

Sonnet 4.6 is Anthropic's most capable Sonnet-class model yet, with frontier performance across coding, agents, and professional work. It excels at iterative development, complex codebase navigation, end-to-end project management with memory, polished document creation, and confident computer use for web QA and workflow automation.

Opus 4.7 is the next generation of Anthropic's Opus family, built for long-running, asynchronous agents. Building on the coding and agentic strengths of Opus 4.6, it delivers stronger performance on complex, multi-step tasks and more reliable agentic execution across extended workflows. It is especially effective for asynchronous agent pipelines where tasks unfold over time - large codebases, multi-stage debugging, and end-to-end project orchestration.

Beyond coding, Opus 4.7 brings improved knowledge work capabilities - from drafting documents and building presentations to analyzing data. It maintains coherence across very long outputs and extended sessions, making it a strong default for tasks that require persistence, judgment, and follow-through.

Claude Opus 4.8 is Anthropic's most capable generally available model in the Opus family. It supports text, image, and file inputs with text output, with reasoning support and a 1M-token context window. It is suited for highly autonomous agents, long-horizon agentic work, knowledge work, and memory-driven tasks where coherence over extended sessions matters.

It is particularly strong on multi-step reasoning, complex coding, and end-to-end project orchestration - large codebases, multi-stage debugging, and long-running asynchronous agent pipelines. Beyond coding, it handles knowledge work such as drafting documents, building presentations, and analyzing data, maintaining quality across very long outputs.

Claude Fable 5 is Anthropic's Mythos-class model, designed for autonomous knowledge work and coding. It accepts text, image, and file inputs, produces text output, and features reasoning capabilities along with a 1M-token context window. The model excels at long-running, complex, and asynchronous tasks that once demanded frequent human oversight.

Its core strength lies in handling end-to-end work that would typically take a person hours, days, or even weeks — tackling problems that are extended, ambiguous, or involve many interdependent steps. It carries out well-defined tasks with minimal errors, self-corrects through built-in verification loops, and comes with robust safeguards.

Claude Sonnet 5 is built to be the most agentic Sonnet model yet. It can plan, use tools such as browsers and terminals, and operate autonomously at a level that only recently required larger and more expensive models.

Claude Opus 5 is Anthropic’s flagship Opus-series model for advanced reasoning, coding, and high-value knowledge work, delivering frontier-level performance close to Claude Fable 5 at roughly half the cost. It supports text, image, and file inputs with text output, offers a 1M-token context window, and is well suited for complex software engineering, scientific research, and long-horizon agentic workflows.

Claude Fable 5.1 is Anthropic’s latest model for demanding reasoning and long-horizon agentic work, with stronger performance in long-running coding, multistep research, and document, spreadsheet, and slide workflows. It supports text and image inputs, text output, a 1M-token context window, and adaptive thinking that is always on with effort-based steering.

Claude Opus 5.5 is Anthropic's flagship model for demanding reasoning, coding, and long-horizon agentic work, succeeding Claude Opus 5. It is particularly strong at multi-step changes in large codebases, code review and bug finding, financial and scientific analysis, and reading dense charts, diagrams, and screenshots, and it is more careful than its predecessor about only stating figures and citing sources it can back up.

The model completes comparable tasks in fewer steps and with fewer tokens than Opus 5, and reports on its work in plainer language, with clear updates on what it did, what it found, and what it needs from the user. Thinking is always adaptive, so effort is the main lever for trading off depth, latency, and cost, and lower effort settings remain effective for latency-sensitive workloads.

Claude Sonnet 5.5 is Anthropic’s upgraded Sonnet-class model, delivering stronger performance than Claude Sonnet 5 while running over 30% faster and at lower cost for many workloads. It is designed for agentic coding, tool use, and everyday professional tasks, making it well suited for developers and teams building fast, capable AI agents.