Claude Sonnet 4.5 could be your next breakthrough coding tool – how to access it today
Anthropic Follow ZDNET: Add us as a preferred source on Google. ZDNET’s key takeaways Anthropic’s latest model, Claude Sonnet 4.5, is here. It scored very highly on coding benchmarks. Claude Code also got long-awaited upgrades. Anthropic’s coding tools have become well-regarded amongst developers, with its Claude 4 Sonnet model, released in May, serving as a free and…
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ZDNET’s key takeaways
- Anthropic’s latest model, Claude Sonnet 4.5, is here.
- It scored very highly on coding benchmarks.
- Claude Code also got long-awaited upgrades.
Anthropic’s coding tools have become well-regarded amongst developers, with its Claude 4 Sonnet model, released in May, serving as a free and reliable coding assistant for many. Just months later, Anthropic has released its next-generation model, featuring upgrades to its performance across the board.
Also: Anthropic’s free Claude Sonnet 4 aced my coding tests – but its paid Opus model somehow didn’t
Claude Sonnet 4.5 is now available, the company said Wednesday, claiming it is the “best coding model in the world” as well as the best model for building complex agents, utilizing computers, and gaining reasoning and mathematical capabilities. Anthropic also launched updates across its Claude Code offering, Claude for Chrome extension, and more.
What’s new in Claude 4.5 Sonnet?
If you have been closely tracking Anthropic’s releases, you may recall that in May, Claude Opus 4 and Sonnet 4 scored highest amongst frontier models on the industry-standard software engineering benchmark test (SWE-bench), which evaluates LLMs’ abilities to solve real-world software engineering tasks sourced from GitHub. Claude Opus 4.1, released in August, surpassed it.
Now, Claude Sonnet 4.5 has lapped that last model, outperforming it on the SWE-bench Verified evaluation, a human-filtered subset of the SWE-bench. Claude Sonnet 4.5 also outperformed leading models from competitors, including GPT-5 Codex, GPT-5, and Gemini 2.5 Pro.
Anthropic said that on the SWE-bench Verified, Sonnet 4.5 held its focus for more than 30 hours on complex, multi-step tasks. This capability is specifically useful for agentic tasks, which oftentimes require solo work in the background for extended periods of time.
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Other improvements include its performance on computers, as indicated by its score on the OSWorld benchmark, which tests the performance of 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%,” Anthropic noted in the release.
The Claude for Chrome extension, now rolled out to everyone who joined the waitlist last month, uses these capabilities. Anthropic also saw improvements across math and reasoning.
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Claude Sonnet 4.5 is also Anthropic’s “most aligned” frontier model yet, according to the company. This means it’s the model that adheres most closely to humans’ instructions and intended use cases, and that has reduced instances of behaviors such as sycophancy and deception. The model is also better at resisting prompt injection attacks and has AI Safety Level 3 (ASL-3) protections on Anthropic’s model framework.
How to access
Claude Sonnet 4.5 is available everywhere, including in the Claude.ai chatbot. Of course, developers and professionals can access the new model in the API and Claude Code, and for the same price as Sonnet 4.
Other upgrades
Anthropic also upgraded its other coding offerings, starting with Claude Code, which now has checkpoints that allow users to save progress and revisit a previous state. It also has what Anthropic is calling a “refreshed” terminal interface and a native VS Code extension.
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Anthropic also launched the Claude Agent SDK, which is the same infrastructure that powers Claude Code, allowing developers to build their own agents with it.
The Claude Code API has introduced a new context editing feature and a memory tool that enables agents to work more efficiently and tackle more complex problems, according to the company. The company also upgraded Claude apps so they can execute code and create files in chat.