Anthropic

Anthropic is an AI safety company and research lab founded in 2021 by former OpenAI researchers Dario Amodei and Daniela Amodei, among others. Its commercial product is the Claude API — a family of large language models (Haiku, Sonnet, Opus) characterized by long context windows (up to 200K tokens), strong instruction following, nuanced reasoning, and safety-first training via Constitutional AI and RLHF methodologies. Claude's 200K token context window (the largest available in production APIs) enables processing entire codebases, legal documents, academic papers, and lengthy conversation histories in a single API call — a significant differentiator from GPT-4's standard 128K context. Anthropic's Extended Thinking feature (claude-sonnet-4-5 and claude-opus-4) enables chain-of-thought reasoning similar to OpenAI o1, surfacing the model's reasoning process for improved accuracy on complex analytical tasks. Anthropic's tool use (function calling) API enables multi-tool AI agent architectures, and Claude's performance on the MMLU, HumanEval, and GSM8K benchmarks consistently places it among the top 2–3 frontier models across coding, reasoning, and language understanding tasks.