Anthropic Claude

Claude is the family of large language models built by Anthropic, an AI safety company founded by former OpenAI researchers. Claude ships as a consumer chat app, a developer API, and Claude Code, an agentic coding tool that works in your terminal. The models come in tiers trading capability against speed and cost, and they’ve earned a reputation for strong writing, careful instruction-following, long-context document work, and — especially — software engineering tasks.

Claude matters to you as a builder for two reasons. First, it’s a top-tier engine for coding and agentic workflows: many AI-assisted development tools and autonomous agents are built on Claude because it handles long, multi-step tasks reliably and uses tools well. Second, Anthropic’s safety-first approach — including its published research on constitutional AI and model interpretability — shapes how the model refuses, hedges, and follows system prompts, which you need to understand to prompt it effectively. Having a serious alternative to OpenAI also gives you negotiating room on quality, price, and availability.

In practice, you’ll call the Messages API with an x-api-key header, a model name, and a list of user/assistant turns, with a separate system prompt for instructions. You’ll use streaming for chat UIs, tool use to let Claude call your functions, and prompt caching to cut costs when reusing long contexts. Claude is also available through AWS Bedrock and Google Cloud Vertex AI if your infrastructure already lives there.