Anthropic Launches Claude Sonnet 4.5: A Developer-Like AI Model Delivering Autonomous Coding Excellence
Anthropic's Claude Sonnet 4.5, launched in late 2025, redefines AI development by enabling over 30 hours of autonomous coding, surpassing competitors in speed and practical automation.
- • Claude Sonnet 4.5 can autonomously manage complex tasks for over 30 hours, a major improvement from its predecessor's 7 hours.
- • It tops software engineering benchmarks and is claimed as the best coding AI model globally by Anthropic.
- • Companies like Netflix and GitHub report significant productivity and accuracy gains using Claude Sonnet 4.5.
- • Compared to GPT-5 Codex and GLM 4.6, Claude prioritizes speed and cost-efficiency but may compromise creativity in complex coding tasks.
Key details
On September 29, 2025, Anthropic unveiled Claude Sonnet 4.5, its most advanced AI agent to date, setting new standards for autonomy and efficiency in software development tasks. This latest iteration significantly surpasses its predecessor, Claude Opus 4, by autonomously managing complex multi-step workflows for over 30 hours compared to just seven hours previously. Designed as an "AI teammate," Claude Sonnet 4.5 excels in navigating digital environments, including web browsing, spreadsheet manipulation, coding, debugging, and API interaction, aiming to transform the software engineering landscape by mimicking human-like usage.
Anthropic claims Claude Sonnet 4.5 as the "best coding model in the world," a status supported by its top rank on the SWE-bench Verified benchmark for software engineering abilities. The model’s effectiveness is reflected in real-world applications, with Netflix reporting unprecedented accuracy in engineering tasks and GitHub observing significant improvements in multi-step reasoning and code comprehension. Additionally, Claude Sonnet 4.5 offers advantages over competitors such as OpenAI’s GPT-5 Codex and Google DeepMind's Gemini 2.5 Pro, notably in coding speed and cost-efficiency, while providing enhanced capabilities for tooling and autonomous agent workflows.
A detailed technical comparison also highlights Claude Sonnet 4.5’s prioritization of speed and efficiency, albeit at some cost to creative output. For example, in straightforward coding tasks such as portfolio website development, Claude Sonnet delivered the fastest and cleanest results but lagged behind GPT-5 Codex in creativity and design innovation. More complex tasks revealed that while GPT-5 excelled in playable outputs, Claude Sonnet struggled with quality, underscoring the model’s focus on speed and practical functionality rather than artistic design.
Jared Kaplan, Anthropic’s co-founder and chief science officer, emphasized the model's enhanced intelligence and collaborative nature, noting that users find Claude Sonnet 4.5 enjoyable to work with. With a market valuation of $183 billion and backing from Amazon, Anthropic aims to drive adoption among SaaS and developer tool startups, particularly in India, where Claude’s capabilities in debugging, cybersecurity, and automation promise to empower globally competitive AI-powered products.
Claude Sonnet 4.5 thus represents a significant technological leap toward autonomous AI agents capable of sustaining extended, intricate development workflows, marking a shift from passive assistants to sophisticated collaborators in software engineering and business automation.