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anthropic.com › news › claude-sonnet-4-5

Introducing Claude Sonnet 4.5

September 29, 2025 - Claude Sonnet 4.5 is the best coding model in the world. It's the strongest model for building complex agents. It’s the best model at using computers.

Talk with Claude, an AI assistant from Anthropic

Discussions

Claude Sonnet 4.5 release tomorrow 9/19

you are looking at javascript that is trying to interpret the url slug that you typed in, you are seeing what you typed in being repeated back to you. like this is web dev 101 shit. if you go to this url you'll see the same pattern, but i'm gonna guess we ain't getting free chicken and fries tomorrow either - https://www.anthropic.com/news/free-chicken-wings-and-fries-for-everyone More on reddit.com

r/ClaudeAI

16

0

August 16, 2025

I tested GPT-5.1 Codex against Sonnet 4.5, and it's about time Anthropic bros take pricing seriously.

I use codex to audit everything that CC produces.. it’s been quite effective More on reddit.com

r/ClaudeAI

206

718

November 15, 2025

Claude Sonnet 4.5 is here!

Yes papi More on reddit.com

r/ClaudeAI

101

472

August 19, 2025

Claude Sonnet 4.5’s Bold Claims Don’t Match What Software Developers Are Seeing

Lol and they are claiming this as the "best Coding model in the world" More on reddit.com

r/webdev

140

579

August 24, 2025

Videos

Sonnet 4.5 is the best coding model in the world - YouTube

September 30, 2025

Claude Sonnet 4.5 - The New Coding King? (Sonnet 4.5 vs. GPT 5 ...

September 29, 2025

Hello Claude Sonnet 4.5! This thing is a BEAST! - YouTube

September 30, 2025

New Claude Sonnet 4.5 Just Broke EVERY Limit We Knew (So Powerful ...

September 30, 2025

Claude Sonnet 4.5 is HERE + Claude Code Upgrades - YouTube

September 30, 2025

r/GithubCopilot on Reddit: Claude Sonnet 4's 1M Context Window ...

anthropic.com › claude › sonnet

Claude Sonnet 4.5

September 29, 2025 - Claude Sonnet 4.5 amplifies GitHub Copilot's core strengths. Our initial evals show significant improvements in multi-step reasoning and code comprehension—enabling Copilot's agentic experiences to handle complex, codebase-spanning tasks better.

platform.claude.com › docs › en › about-claude › models › whats-new-claude-4-5

What's new in Claude 4.5 - Claude Docs

1 month ago - Features a more accessible price point than previous Opus models. Available with a 200k token context window. Claude Sonnet 4.5: Our best model for complex agents and coding, with the highest intelligence across most tasks.

aws.amazon.com › blogs › aws › introducing-claude-sonnet-4-5-in-amazon-bedrock-anthropics-most-intelligent-model-best-for-coding-and-complex-agents

Introducing Claude Sonnet 4.5 in Amazon Bedrock: Anthropic’s most intelligent model, best for coding and complex agents | Amazon Web Services

September 29, 2025 - Claude Sonnet 4.5 demonstrates advancements in agent capabilities, with enhanced performance in tool handling, memory management, and context processing. The model shows marked improvements in code generation and analysis, from identifying optimal ...

docs.claude.com › en › docs › about-claude › models › whats-new-claude-4-5

What's new in Claude 4.5 - Claude Docs

October 16, 2025 - Claude Haiku 4.5: Our fastest and most intelligent Haiku model with near-frontier performance. The first Haiku model with extended thinking · Claude Sonnet 4.5 is our best coding model to date, with significant improvements across the entire ...

coderabbit.ai › blog › claude-sonnet-45-better-performance-but-a-paradox

Claude Sonnet 4.5: Better performance but a paradox

October 3, 2025 - We benchmarked Claude Sonnet 4.5 as it narrows the gap with Opus 4.1 in code review, catching more critical bugs with 41% important hits at lower cost.

medium.com › data-science-in-your-pocket › claude-4-5-sonnet-bye-bye-software-devs-7c35c244e357

Claude 4.5 Sonnet : Bye bye Software Devs | by Mehul Gupta | Data Science in Your Pocket | Medium

September 30, 2025 - Sonnet 4.5 nails this. On OSWorld, the benchmark that tests computer-use, it now leads at 61.4%, compared to Sonnet 4’s 42.2% just four months ago. On SWE-bench Verified, which measures real-world software engineering tasks, it sits firmly at the top. This is where it earns the title of best coding model. ... Anthropic didn’t just ship the model, they overhauled the ecosystem. Claude Code: checkpoints (finally), a better terminal, and a native VS Code extension.

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cloud.google.com › blog › products › ai-machine-learning › announcing-claude-sonnet-4-5-on-vertex-ai

Announcing Claude Sonnet 4.5 on Vertex AI | Google Cloud Blog

September 30, 2025 - Claude Sonnet 4.5 is built to work independently for hours, maintaining clarity while orchestrating tools and coordinating multiple agents to solve complex problems. It’s designed to excel at long-running tasks with enhanced domain knowledge in coding, finance, research, and cybersecurity.

lesswrong.com › posts › 4yn8B8p2YiouxLABy › claude-sonnet-4-5-system-card-and-alignment

Claude Sonnet 4.5: System Card and Alignment

September 30, 2025 - Claude Sonnet 4.5 did as requested, showing asymmetry only 3.3% of the time, versus 15.3% for Sonnet 4, with most differences being caveats, likely because a lot more than 3.3% of political questions have (let’s face it) a directionally correct answer versus a theoretically ‘neutral’ position.

poe.com › Claude-Sonnet-4.5

Claude-Sonnet-4.5 - Poe

September 29, 2025 - Claude Sonnet 4.5 represents a major leap forward in AI capability and alignment. It is the most advanced model released by Anthropic to date, distinguished by dramatic improvements in reasoning, mathematics, and real-world coding. Supports 1m tokens of context.

reddit.com › r/claudeai › claude sonnet 4.5 release tomorrow 9/19

Claude Sonnet 4.5 release tomorrow 9/19 : r/ClaudeAI

August 16, 2025 - Claude model this month. ... Excited, but I am actually low key waiting for a new version of Haiku. Does anyone know why they didn't release a version after 3.5? ... Wait 4.5 So what difference does version 1 make? I don't know if they'll release it. I'm also really looking forward to Haiku because it will be free to use in Websim and other websites/AI apps.

datacamp.com › blog › claude-sonnet-4-5

Claude Sonnet 4.5: Tests, Features, Access, Benchmarks, and More | DataCamp

September 30, 2025 - Anthropic has just released its latest model, Claude Sonnet 4.5, with some impressive claims: they’re hailing it as “the best coding model in the world” as well as touting it as the top model for building complex agents and computer use.

simonwillison.net › 2025 › Sep › 29 › claude-sonnet-4-5

Claude Sonnet 4.5 is probably the “best coding model in the world” (at least for now)

September 29, 2025 - Claude Sonnet 4.5 is the best coding model in the world. It’s the strongest model for building complex agents. It’s the best model at using computers.

reddit.com › r/claudeai › i tested gpt-5.1 codex against sonnet 4.5, and it's about time anthropic bros take pricing seriously.

r/ClaudeAI on Reddit: I tested GPT-5.1 Codex against Sonnet 4.5, and it's about time Anthropic bros take pricing seriously.

November 15, 2025 -

I've used Claude Sonnets the most among LLMs, for the simple reason that they are so good at prompt-following and an absolute beast at tool execution. That also partly explains the maximum Anthropic revenue from APIs (code agents to be precise). They have an insane first-mover advantage, and developers love to die for.

But GPT 5.1 codex has been insanely good. One of the first things I do when a new promising model drops is to run small tests to decide which models to stick with until the next significant drop. Also, allows dogfooding our product while building these.

I did a quick competition among Claude 4.5 Sonnet, GPT 5, 5.1 Codex, and Kimi k2 thinking.

Test 1 involved building a system that learns baseline error rates, uses z-scores and moving averages, catches rate-of-change spikes, and handles 100k+ logs/minute with under 10ms latency.
Test 2 involved fixing race conditions when multiple processors detect the same anomaly. Handle ≤3s clock skew and processor crashes. Prevent duplicate alerts when processors fire within 5 seconds of each other.

The setup used models with their own CLI agent inside Cursor,

Claude Code with Sonnet 4.5
GPT 5 and 5.1 Codex with Codex CLI
Kimi K2 Thinking with Kimi CLI

Here's what I found out:

Test 1 - Advanced Anomaly Detection: Both GPT-5 and GPT-5.1 Codex shipped working code. Claude and Kimi both had critical bugs that would crash in production. GPT-5.1 improved on GPT-5's architecture and was faster (11m vs 18m).
Test 2 - Distributed Alert Deduplication: Codexes won again with actual integration. Claude had solid architecture, but didn't wire it up. Kimi had good ideas, but a broken duplicate-detection logic.

Codex cost me $0.95 total (GPT-5) vs Claude's $1.68. That's 43% cheaper for code that actually works. GPT-5.1 was even more efficient at $0.76 total ($0.39 for test 1, $0.37 for test 2).

I have written down a complete comparison picture for this. Check it out here: Codexes vs Sonnet vs Kimi

And, honestly, I can see the simillar performance delta in other tasks as well. Though for many quick tasks I still use Haiku, and Opus for hardcore reasoning, but GPT-5 variants have become great workhorses.

OpenAI is certainly after that juicy Anthropic enterprise margins, and Anthropic really needs to rethink its pricing.

Would love to know your experience with GPT 5.1 and how you rate it against Claude 4.5 Sonnet.

I use codex to audit everything that CC produces.. it’s been quite effective

I've been using Codex when I exhaust my Claude weekly limit, and vice-versa. So far so good for $40/mo. I had Gemini Pro too before, but it destroys my code, and with confidence lol, so I fired him form our team.

reddit.com › r/claudeai › claude sonnet 4.5 is here!

r/ClaudeAI on Reddit: Claude Sonnet 4.5 is here!

August 19, 2025 -

https://www.an.com/news/claude-sonnet-4-5

And Claude Code v2.0!

reddit.com › r/webdev › claude sonnet 4.5’s bold claims don’t match what software developers are seeing

r/webdev on Reddit: Claude Sonnet 4.5’s Bold Claims Don’t Match What Software Developers Are Seeing

August 24, 2025 - Sonnet 4 was hobbled and completely unimpressive in Cursor. I only ever used Gemini 2.5 and GPT-5. 4.5 is in a completely different league. And in Claude Code having been previously spoiled by plan mode I noticed myself trusting 4.5 to plan and execute a lot more (sometimes out of shear laziness).

reddit.com › r/singularity › claude 4.5 sonnet is here

r/singularity on Reddit: Claude 4.5 Sonnet is here

September 29, 2025 -

https://www.anthropic.com/news/claude-sonnet-4-5

Am I tripping or is this actually a pretty nice upgrade

Enhanced tool usage: The model more effectively uses parallel tool calls, firing off multiple speculative searches simultaneously during research and reading several files at once to build context faster. Improved coordination across multiple tools and information sources enables the model to effectively leverage a wide range of capabilities in agentic search and coding workflows. three weeks ago amidst all the claude inference issues, i made a comment about sonnet feeling way faster like it was doing parallel tool calls , now i'm thinking i was A/B tested on. i'd never seen sonnet perform that well before

every.to › vibe-check › vibe-check-claude-sonnet-4-5

Vibe Check: Claude Sonnet 4.5

September 29, 2025 - Anthropic just rolled out Claude Sonnet 4.5, and, of course, we spent the weekend using it to code and running long agentic tasks with it.

techcrunch.com › home › anthropic launches claude sonnet 4.5, its best ai model for coding

Anthropic launches Claude Sonnet 4.5, its best AI model for coding | TechCrunch

September 29, 2025 - On Monday, Anthropic launched a new frontier model called Claude Sonnet 4.5, which it claims offers state-of-the-art performance on coding benchmarks.