Claude

Claude is a series of large language models developed by Anthropic and first released in 2023. Since Claude 3, each generation has typically been released in three sizes, from least to most capable: Haiku, Sonnet, and Opus. An additional model named Claude Mythos was released to a handful of companies in 2026 but not to the public.

Claude is used for software development via Claude Code. Claude is trained using "constitutional AI", a technique developed by Anthropic to improve ethical and legal compliance (AI alignment). The name Claude has been described both as a tribute to Claude Shannon, who pioneered information theory, and as a friendly, male-gendered counterpart to virtual assistants like Alexa and Siri.

US federal agencies started phasing out the use of Claude after Anthropic refused to remove contractual prohibitions on the use of Claude for mass domestic surveillance and fully-autonomous weapons. Following the refusal, the Department of Defense designated the company a "supply chain risk" and barred all U.S. military private contractors, suppliers, and partners from doing business with the firm. On March 26, 2026, a federal judge issued a temporary injunction against the DoD's designation.