Claude
Anthropic's LLM family — named after Claude Shannon. Comes as Opus (powerful), Sonnet (balanced), Haiku (fast, cheap).
Founded 2021 by Dario and Daniela Amodei (ex-OpenAI) and other GPT-3 architects. Trained with Constitutional AI — the model learns values via a written constitution + RLAIF. Famous for long context windows (200k tokens default, 1M experimental) and "Extended Thinking" mode (reasoning à la o1).
Available via claude.ai, the Anthropic API, AWS Bedrock and GCP Vertex AI. Strong at code, long-form writing, agentic tool use. Competes with GPT-4o and Gemini 2.5 in the frontier segment.