Anthropic's Sonnet-tier model announced on September 29, 2025, with major coding, instruction-following, and agentic improvements at the same price as Sonnet 4. The same announcement added the context editing feature and a memory tool to the Claude API.
QUICK FACTS
WHY WE PICKED IT
Sonnet 4.5 brought meaningful coding and agentic upgrades at the same price as Sonnet 4, making it a notable missing mid-tier entry.
OFFICIAL LINKS
SIMILAR TOOLS
PRICING
Requires a paid subscription.
FEATURED IN GUIDES
The most-starred CLAUDE.md on GitHub has four rules, not twelve, and the error rates everyone quotes...
The benchmark gap has largely closed: open models now score within a point of the closed frontier on...
Capacity decides whether a model runs. Bandwidth decides how fast it talks, and it is the number mos...
Running a frontier open model locally is a memory problem before it is a speed problem, and a bandwi...
Abliteration removes a model's ability to refuse by deleting one direction from its activations. It ...
EXPLORE ALTERNATIVES
Compare Claude Sonnet 4.5 with 5+ similar llms AI tools.
FREQUENTLY ASKED QUESTIONS
Is Claude Sonnet 4.5 free?
No, Claude Sonnet 4.5 requires a paid subscription.
Does Claude Sonnet 4.5 have an API?
Yes, Claude Sonnet 4.5 offers an API for programmatic integration.
What is Claude Sonnet 4.5 best for?
Claude Sonnet 4.5 is best for Balanced Coding Agents. Anthropic's Sonnet-tier model announced on September 29, 2025, with major coding, instruction-following, and agentic improvements at the same price as Sonnet 4. Sonnet 4.5 brought meaningful coding and agentic upgrades at the same price as Sonnet 4, making it a notable missing mid-tier entry.
What platforms does Claude Sonnet 4.5 support?
Claude Sonnet 4.5 supports web, api.
Is Claude Sonnet 4.5 open source?
No, Claude Sonnet 4.5 is not open source.
How do I use Claude Sonnet 4.5?
Claude Sonnet 4.5 is a large language model for text generation, analysis, and conversation. Access through the web interface. Enter prompts or questions to get responses.
FEATURED ON CURATEDAI
Work on Claude Sonnet 4.5? You're hand-reviewed in our directory. Add this badge to your site — it links back to this profile.
