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Claude Sonnet 4.5 vs GPT-5 Codex
Comprehensive side-by-side LLM comparison
Claude Sonnet 4.5 leads with 4.5% higher average benchmark score. Claude Sonnet 4.5 supports multimodal inputs. Claude Sonnet 4.5 is available on 3 providers. Both models have their strengths depending on your specific coding needs.
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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 Codex, released by OpenAI in August 2025, is a coding-specialized large language model from the GPT-5 family engineered for software engineering, code generation, and agentic development workflows. It builds on GPT-5's architecture with optimizations targeting multi-file code editing, test generation, and automated debugging. GPT-5 Codex targets developers and agentic coding tools requiring a model tuned specifically for programming tasks.
1 month newer
GPT-5 Codex
OpenAI
2025-08
Claude Sonnet 4.5
Anthropic
2025-09-29
Performance Metrics
Context window and performance specifications
Average performance across 3 common benchmarks
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Claude Sonnet 4.5
Average Score:58.4%(+4.5%)
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GPT-5 Codex
Average Score:54.0%
Performance comparison across key benchmark categories
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Claude Sonnet 4.5
Coding58.4%(+4.5%)
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GPT-5 Codex
Coding54.0%
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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 Codex
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Claude Sonnet 4.5
Avg Score:58.4%(+4.5%)
Providers:3
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GPT-5 Codex
Avg Score:54.0%
Providers:0