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Claude Sonnet 4.5 - AI Tool Review, Pricing & Features | AIDevStart

Directory LLM ModelsClaude Sonnet 4.5

Claude Sonnet 4.5

Claude Sonnet 4.5

The perfect balance of speed and intelligence.

Claude Sonnet 4.5 (Sep 2025) balances Opus-level reasoning with Sonnet-level speed, making it the default choice for most agentic coding tasks.

Last updated February 3, 2026

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Pros and Cons

Pros

80.2% on SWE-bench
200k context
Cheaper than Opus

Cons

Paid API

Use Cases

Daily coding

Refactoring

Test generation

Overview

Claude 3.5 Sonnet -> Claude Sonnet 4.5 (Sep 2025)

Rating: 9.7/10 (The Workhorse)

1. Executive Summary

Released in September 2025, Claude Sonnet 4.5 quickly became the default model for most developers. It balances the reasoning depth of Opus with the speed of Sonnet.

2. Key Improvements

Coding Performance: 80.2% on SWE-bench (Verified).
Context: 200k tokens with near-perfect recall.
Cost: Significantly cheaper than Opus 4.5 while beating GPT-5 in many coding benchmarks.

Tool Details

CategoryLLM Models

PricingPaid

Platforms

APIClaude.aiCursorWindsurf

Versions

Sonnet 4.5

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