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.
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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.
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PRICING
Requires a paid subscription.
FEATURED IN GUIDES
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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 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.
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