Claude 3.5 Sonnet, released June 20, 2024, was the model that made Claude a default choice for developers. Despite being a mid-tier model, it outperformed the larger Claude 3 Opus while running roughly twice as fast at a fraction of the cost, and its coding and vision abilities set a new bar for the price point. It launched together with Artifacts in the Claude app, which turned chat output into live, editable documents and code.

On benchmarks it jumped to 59.4% on GPQA Diamond — nine points over Opus — and it became the base of one of the most-used model lines in AI-assisted programming. An upgraded version followed on October 22, 2024, lifting SWE-Bench Verified to 49.0% and introducing computer use, before Claude 3.7 Sonnet succeeded the line in February 2025.