Anthropic's Claude Sonnet 4.5: AI Coder Works 30 Hours Straight, Produces Production-Ready Apps

Anthropic Redefines AI Coding with Claude Sonnet 4.5: 30-Hour Development Marathon

Anthropic, a leader in AI safety and research, has unveiled Claude Sonnet 4.5, a groundbreaking AI model designed to revolutionize software development. Marketed as the "most advanced AI for programming" by its creators, Sonnet 4.5 isn't just about generating snippets; it's engineered to produce production-ready applications and demonstrate an astonishing capacity for sustained, uninterrupted coding. This leap forward was vividly illustrated in a recent test where the AI autonomously developed an application akin to Slack, a monumental task that spanned approximately 30 hours. This incredible feat eclipses previous AI benchmarks, including Anthropic's own prior records and OpenAI's GPT-5-Codex, by a factor of four.

Beyond Code Generation: A Holistic Development Partner

The capabilities of Claude Sonnet 4.5 extend far beyond mere code composition. David Hershi, an AI researcher at Anthropic, shared with TechCrunch that during its 30-hour coding session, the AI was concurrently managing essential backend operations. This included ensuring database services were functional, acquiring domain names, and even navigating the rigorous SOC 2 audit process to guarantee the security and compliance of the nascent application. This multi-faceted approach transforms the AI from a mere coding assistant into a comprehensive development partner, capable of handling complex, real-world project requirements.

Performance Benchmarks and Superior Agentic Capabilities

Claude Sonnet 4.5 is making significant waves in the realm of software engineering. It achieved an impressive 77.2% on the SWE-bench Verified test, a metric designed to gauge an AI's efficacy in tackling authentic software engineering challenges. Across a spectrum of benchmarks, Sonnet 4.5 shows an average improvement of 3%. Notably, its prowess in interacting with PCs and various services has seen a dramatic surge, leaping from 42% to 61% in performance. This enhanced interaction capability is crucial for agentic tasks, where the AI must understand and act within complex digital environments, further solidifying Sonnet 4.5's superiority over older Anthropic models in both coding and agentic applications.

Unprecedented Safety and Robust Security Measures

Anthropic's commitment to AI safety is a cornerstone of their development philosophy, and Claude Sonnet 4.5 represents a significant stride in this direction. The company proudly declares it as their "safest AI system to date," thanks to extensive security training. This robust conditioning significantly mitigates issues like sycophancy, deception, and hallucinations – troublesome traits that have plagued other AI models, notably OpenAI's in recent months. Anthropic has further fortified Sonnet 4.5 with advanced filters designed to preemptively block potentially dangerous outputs, including those related to chemical, biological, and nuclear weapons, ensuring a more responsible and secure AI interaction.

Accessibility and Expanded Developer Toolkit

Anthropic is making Claude Sonnet 4.5 widely accessible. Developers can integrate its powerful capabilities through the Claude API, and it will also be available within the Claude chatbot interface, even for free users, albeit with certain limitations. The pricing structure for developers is set at $3 per 1 million input tokens and $15 per 1 million output tokens. Beyond the core model, Anthropic has also rolled out several complementary updates. The Claude Agent SDK, the foundational technology for Anthropic's AI agents, is now publicly available. The Claude API now features 'persistent memory,' allowing for the intelligent pruning of context. Claude Code has introduced backup functionality with a `/rewind` command to revert to the last saved state, alongside a `/usage` command for quick limit checks. Complementing these advancements, a previously released Chrome extension seamlessly integrates Claude into the browser, further enhancing user experience and productivity.