Anthropic launched mid-range AI model Claude Sonnet 5.5 on September 29, featuring superior coding capabilities that surpass flagship Opus 5.5 in tests, alongside comparable general reasoning skills. Priced at just $2 per million input tokens and $10 for output, it offers a 30% cost reduction due to efficient reasoning. The model includes upgraded security measures, such as routing high-risk requests to older models and adding anti-plagiarism protections, significantly lowering access barriers for developers while maintaining strong performance across key benchmarks.