Anthropic has announced the release of Claude Sonnet 4.5, the latest version of its Claude family of AI models, which the company is describing as its most capable tool for software development so far. One of the main improvements is that Claude Sonnet 4.5 can run on its own for much longer.
Anthropic released tests showing Sonnet 4.5 it can stay active for up to 30 hours, compared with about seven hours in earlier versions. This allows it to take on longer projects without restarting or losing track, like fixing bugs across large codebases or building applications from scratch.
The AI startup, which was founded by former OpenAI senior leaders, has also shown that the model can create entire programs, not just short pieces of code. In one demonstration, it wrote more than 11,000 lines of code to produce a working web app. On coding benchmarks, including SWE-Bench, it outperformed earlier Claude models and now ranks among the top AI tools for software engineering.
“On OSWorld, a benchmark that tests AI models on real-world computer tasks, Sonnet 4.5 now leads at 61.4%. Just four months ago, Sonnet 4 held the lead at 42.2%,” the company informed.
Anthropic has positioned Sonnet 4.5 not just as a coding assistant but also as an ‘agentic’ model. This means the model can interact more effectively with computer systems, simulating clicks, typing, navigation, and tool use in order to carry out multi-step workflows. With these improvements, it can function less like a text-only chatbot and more like a digital coworker able to manage parts of real-world tasks from start to finish. This also represents Anthropic’s answer to the growing trend of AI agents.
For businesses, Claude Sonnet 4.5 is being marketed as a practical and safe solution, especially in regulated or high-stakes industries where reliability is essential. At the same time, Anthropic (backed by major investors including Amazon and Google) is widening access through partnerships. One prominent example is Microsoft’s 365 Copilot, where Claude’s technology is built into popular apps like Word, Excel, and Outlook.
The launch of Claude Sonnet 4.5 comes as competition in AI is heating up. OpenAI, Google, and others are all rolling out newer and more powerful systems. For example, OpenAI has been advancing its GPT line (like GPT-5), while Google’s Gemini models are also competing strongly in reasoning and coding tasks.
The timing of the release becomes more significant since just weeks earlier, the company raised $13 billion in its Series F funding round, bringing its post-money valuation to $183 billion. At that time, the firm revealed that it now serves over 300,000 business customers, with large accounts (those generating over $100,000 in annual revenue) growing nearly seven times in the past year. It also reported that since its full launch in May 2025, its ‘Claude Code’ has quickly become popular with developers, generating over $500 million in run-rate revenue and seeing usage grow more than ten times in just three months.
But despite all such advancements and efforts, the company is still not free from controversies and challenges. Anthropic remains unprofitable, dealing with high costs for computing, data processing, and hiring top research talent. It has also faced legal troubles, like in June 2025, when Reddit sued the company for using its content without permission.
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