Anthropic Launches Claude Sonnet 5: Near-Opus Performance at a Lower Price

AI company Anthropic today announced a major upgrade to its Claude model lineup, officially launching Claude Sonnet 5 to replace the Sonnet 4.6 released in February. This positions Sonnet 5 as the new mid-range workhorse in Anthropic's product line, sitting between the lightweight Haiku and flagship Opus. The upgrade aims to deliver performance close to the high-end model at a significantly lower cost.

According to Anthropic, Sonnet 5 is described as "the most agentic Sonnet model yet." It can autonomously create plans, invoke external tools like browsers and terminals, and execute complex tasks without continuous human oversight. Anthropic says Sonnet 5 has narrowed the performance gap with Opus 4.8 considerably, while offering markedly lower usage costs—making it an ideal choice for businesses balancing intelligence and budget.

Starting today, Sonnet 5 is the default model for Claude Free and Pro users. Pricing includes a limited-time offer: through August 31, 2026, input tokens cost $2 per million tokens and output tokens cost $10 per million tokens. This pricing strategy aims to attract more developers and enterprise customers into the Claude ecosystem while maintaining competitive pressure on rivals.

Takeaway: The launch of Sonnet 5 underscores the growing trend of "lightweight, cost-effective" AI models. As large models remain expensive, mid-tier models that achieve near-flagship performance through optimized architecture could become the key breakthrough for large-scale industry deployment.