--- source: 'https://howaiworks.ai/ai-tools/claude' section: ai-tools title: Claude description: >- Anthropic's family of AI models and assistants, led by Claude Fable 5.1 and Claude Opus 5, with frontier reasoning, agentic coding and 1M-token context. category: Text & Writing developer: Anthropic projectType: Web Application & API pricing: Freemium launchDate: '2023-03-14' modelUsed: Claude Fable 5.1 / Opus 5 / Sonnet 5 / Haiku 4.5 officialWebsite: 'https://claude.ai' pricingPage: 'https://www.claude.com/pricing' tags: - AI Assistant - Language Model - Productivity - Anthropic - Claude Opus 5 - Agentic AI - Large Context Window difficultyLevel: Beginner setupTime: 1 minute apiAvailable: true integrationTypes: - Web - API - Mobile - Slack - CLI isReviewed: true toolLevel: popular lastUpdated: '2026-09-06' --- # Claude > Anthropic's family of AI models and assistants, led by Claude Fable 5.1 and Claude Opus 5, with frontier reasoning, agentic coding and 1M-token context. Claude is a family of large language models developed by Anthropic, designed to be helpful, honest, and harmless. Known for its sophisticated reasoning capabilities and advanced understanding of complex context, Claude has become a leading alternative in the conversational AI space. ## Overview Developed by former OpenAI executives, Anthropic's Claude is built using "Constitutional AI," a method that gives the model a set of principles to follow during training. This approach helps ensure that Claude remains safe and helpful while maintaining high performance. Claude is available through a web interface at [claude.ai](https://claude.ai), various API integrations, and specialized tools like **[Claude Code](https://howaiworks.ai/ai-tools/claude-code)** for developers. ## Key Features - **Advanced Reasoning**: State-of-the-art performance on complex logical, creative, and engineering tasks. - **Large Context Window**: Fable 5.1, Opus 5, and Sonnet 5 process up to 1M tokens in a single prompt; Haiku 4.5 handles 200K. - **Vision**: Image understanding for technical drawings, screenshots, and UI analysis. - **Agentic Capabilities**: Optimized for long-running workflows and complex software engineering tasks. - **Artifacts**: A dedicated UI space for viewing and interacting with code, documents, and websites generated by Claude. - **Cheap Cache Reads on Fable 5.1**: A prompt-cache read costs $0.25 per million tokens — 2.5% of base input price, where every other Claude model charges 10%. Long agentic sessions that replay a large cached prefix on every turn pay a quarter of the old rate. - **Safety First**: Built with updated Constitutional AI protocols to ensure reliable and helpful outputs. ## Models Anthropic offers different versions of Claude to suit various needs: - **[Claude Fable 5.1](https://howaiworks.ai/models/claude-fable)**: Released September 1, 2026. The most capable model Anthropic sells to everyone, aimed at the hardest reasoning and at agents that run for hours. 1M-token context. - **[Claude Opus 5](https://howaiworks.ai/models/claude-opus)**: Anthropic's recommended default for most work, including agentic coding and enterprise workloads. 1M-token context. - **[Claude Sonnet 5](https://howaiworks.ai/models/claude-sonnet)**: High-performance model for coding and agents. 1M-token context. - **[Claude Haiku 4.5](https://howaiworks.ai/models/claude-haiku)**: Anthropic's fastest, most cost-efficient model. 200K-token context. There is no Opus 5.1 or Sonnet 5.1. Fable 5.1 sits *above* the Opus tier rather than replacing it, and Anthropic still points most workloads at Opus 5 first. Fable 5.1 exposes five effort levels — `low`, `medium`, `high`, `xhigh` and `max` — and the default depends on where you are using it: **high in Claude Code**, **medium in Claude Cowork and on Claude.ai**. If a Claude Code session feels slower and more expensive than the same prompt on the web, that difference is why. ## Use Cases ### Coding & Engineering Claude is highly regarded by developers for its ability to write, debug, and explain code. Tools like **[Claude Code](https://howaiworks.ai/ai-tools/claude-code)** extend this power directly to the terminal. ### Content Creation & Analysis - **Summarization**: Quickly summarize long documents or entire books. - **Writing**: Draft emails, reports, and creative content with a natural tone. - **Research**: Analyze and synthesize information from multiple sources. ### Data Analysis - **JSON Processing**: Extracting and formatting data. - **Data Interpretation**: Explaining trends and insights from uploaded files. ## Pricing & Access All prices in **USD**, as published on [claude.com/pricing](https://www.claude.com/pricing). - **Free**: $0. Chat on web, iOS, Android, and desktop, with web search, memory across conversations, and extended thinking. - **Claude Pro**: $17/month billed annually ($200 up front), or $20/month billed monthly. Adds more usage, Claude Code, Claude Cowork, unlimited projects, and Research. - **Claude Max**: From $100/month. Choose 5x or 20x more usage than Pro, higher output limits, and priority access at high traffic times. - **Claude Team**: $20/seat/month billed annually ($25 monthly) for a standard seat; $100/seat/month billed annually ($125 monthly) for a premium seat, which includes Claude Code and Claude Cowork. - **Claude Enterprise**: Contact sales — seat price plus usage at API rates. - **API (Claude Console)**: Pay-as-you-go, per million tokens (input / output): - Fable 5.1 — $10 / $50, with cache reads at $0.25 (down from $1.00 on Fable 5) - Opus 5 — $5 / $25, cache reads $0.50 - Sonnet 5 — $2 / $10, cache reads $0.20. The $2 / $10 rate launched as introductory pricing through August 31, 2026; Anthropic has since made it the standard price and cancelled the planned increase to $3 / $15. - Haiku 4.5 — $1 / $5, cache reads $0.10 Cache reads are 10% of base input on every model except Fable 5.1, which charges 2.5%. Batch processing takes 50% off input and output on all four. ## Getting Started 1. Visit [claude.ai](https://claude.ai). 2. Sign up with your email or Google account. 3. Start chatting or uploading documents for analysis. ## Alternatives - **[ChatGPT](https://howaiworks.ai/ai-tools/chatgpt)** - OpenAI's flagship conversational AI. - **[Gemini](https://howaiworks.ai/ai-tools/google-gemini)** - Google's multimodal AI assistant. - **[Perplexity AI](https://howaiworks.ai/ai-tools/perplexity-ai)** - AI search engine focused on citations. ## Frequently Asked Questions ### Which Claude model should I use? Anthropic recommends Claude Opus 5 as the starting point for most work. Move up to Claude Fable 5.1 for the hardest reasoning and for agents that run for hours; use Claude Sonnet 5 for high-volume coding and agent work, and Claude Haiku 4.5 when speed and cost matter more than depth. ### Is there a Claude Opus 5.1 or a Claude Sonnet 5.1? No. The 5.1 release was Claude Fable 5.1, on September 1, 2026, and it sits above the Opus tier rather than replacing it. Opus 5, Sonnet 5 and Haiku 4.5 all remain current in their own tiers. ### What changed in Claude Fable 5.1? Base pricing did not move — still $10 per million input tokens and $50 per million output. What changed is prompt caching: a cache read costs $0.25 per million tokens instead of $1.00, a 75% cut. Anthropic puts the saving at roughly 25% on a typical workload and up to 45% on highly agentic ones. ### How much does Claude Pro cost? $17 per month billed annually, which is $200 up front, or $20 per month billed monthly. Pro includes Claude Code and Claude Cowork, unlimited projects and Research. ## Related ### Related tools - [ChatGPT](https://howaiworks.ai/ai-tools/chatgpt) - [Google Gemini](https://howaiworks.ai/ai-tools/google-gemini) - [Perplexity AI](https://howaiworks.ai/ai-tools/perplexity-ai) - [Claude Code](https://howaiworks.ai/ai-tools/claude-code) --- Source: https://howaiworks.ai/ai-tools/claude — HowAIWorks.ai