Anthropic released Claude 3.5 Sonnet, a mid-tier model that outperformed the flagship Claude 3 Opus on many benchmarks while running at a fraction of the cost and twice the speed. It became the default model for most developers almost overnight.

The release also introduced Artifacts, a dedicated panel beside the chat where Claude could render documents, code, and interactive content. Artifacts became one of Claude's signature features and a template rivals later copied.

Claude 3.5 Sonnet's long reign — it stayed the developer favorite well into 2025 — made it arguably the most influential single model release of the Claude 3 generation.