Introducing Claude Sonnet 4.5
Introduces Claude Sonnet 4.5, the most capable coding model with improvements in reasoning, math, and computer use. Includes upgrades to Claude Code, API, and product features like checkpoints and VS Code extension.
Anthropic changelog: September 2025
3 releases from to
Everything Anthropic shipped in September 2025, collected from official Anthropic sources. Each entry is dated and links to the page it came from.
September 2025 at a glance
September 2025 was Anthropic's 4th busiest month of the 12 months to then: 3 releases, about 2× its monthly average of 2. That was 1 release fewer than August 2025. Most were Model (2), followed by Product (1).
Releases
3
-1 vs August 2025
Rank of 12 months
4th
Average 1.5 a month
Most shipped
Model
2 releases
Notable Anthropic launches in September 2025
- Model
Introducing Claude Sonnet 4.5
Introduces Claude Sonnet 4.5, the most capable coding model with improvements in reasoning, math, and computer use. Includes upgrades to Claude Code, API, and product features like checkpoints and VS Code extension.
Source: Anthropic - Model
Claude Sonnet 4.5 Launch
Introducing Claude Sonnet 4.5, the most capable coding model with improvements in reasoning, math, and computer use. Includes upgrades to Claude Code, API, and apps, along with the Claude Agent SDK for developers.
Source: Anthropic - Product
Claude Sonnet 4.5
Introducing Claude Sonnet 4.5, the most capable coding model with significant gains in reasoning, math, and computer use. Includes major product upgrades like checkpoints, VS Code extension, and context editing features.
Source: Anthropic
All Anthropic releases in September 2025
Newest first. Each entry links to the official page it came from.
September 20253 releases
Claude Sonnet 4.5 Launch
Introducing Claude Sonnet 4.5, the most capable coding model with improvements in reasoning, math, and computer use. Includes upgrades to Claude Code, API, and apps, along with the Claude Agent SDK for developers.
Claude Sonnet 4.5
Introducing Claude Sonnet 4.5, the most capable coding model with significant gains in reasoning, math, and computer use. Includes major product upgrades like checkpoints, VS Code extension, and context editing features.
Where September 2025 sits
Anthropic releases per month, for September 2025 and the 11 months before it. A taller bar means more releases that month; the dated entries for each month are on its own page.
Other companies in September 2025
8 of the companies we track shipped in September 2025; Anthropic ranks 3rd by number of releases.
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