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Claude Sonnet 4.5 vs GPT-5.1 Codex Max
Comprehensive side-by-side LLM comparison
GPT-5.1 Codex Max leads with 5.4% higher average benchmark score. Claude Sonnet 4.5 supports multimodal inputs. Claude Sonnet 4.5 is available on 3 providers. Overall, GPT-5.1 Codex Max is the stronger choice for coding tasks.
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Anthropic
Claude Sonnet 4.5, released by Anthropic in September 2025, is a large language model from the Claude 4.5 family that balances response quality and efficiency for coding, agentic tasks, and analytical work. It features a 200K token context window (extendable to 1M tokens in beta), 64K maximum output tokens, native image understanding, and extended thinking support. Sonnet 4.5 targets use cases that require a balance of throughput and reasoning depth, including code generation, data analysis, and multi-step agentic pipelines.
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OpenAI
GPT-5.1 Codex Max, released by OpenAI in November 2025, is an enhanced coding variant from the GPT-5.1 Codex line, designed for more complex software engineering tasks requiring additional reasoning depth. It targets large-scale code generation, automated refactoring, and sophisticated agentic development workflows.
1 month newer
Claude Sonnet 4.5
Anthropic
2025-09-29
GPT-5.1 Codex Max
OpenAI
2025-11
Performance Metrics
Context window and performance specifications
Average performance across 2 common benchmarks
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Claude Sonnet 4.5
Average Score:49.0%
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GPT-5.1 Codex Max
Average Score:54.4%(+5.4%)
Performance comparison across key benchmark categories
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Claude Sonnet 4.5
Coding49.0%
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GPT-5.1 Codex Max
Coding54.4%(+5.4%)
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Knowledge Cutoff
Training data recency comparison
Claude Sonnet 4.5
2025-01
More recent knowledge cutoff means awareness of newer technologies and frameworks
Provider Availability & Performance
Available providers and their performance metrics
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Claude Sonnet 4.5
3 providers
Anthropic
AWS Bedrock
Google Cloud Vertex AI
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GPT-5.1 Codex Max
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Claude Sonnet 4.5
Avg Score:49.0%
Providers:3
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GPT-5.1 Codex Max
Avg Score:54.4%(+5.4%)
Providers:0