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GPT-5 Codex vs o3
Comprehensive side-by-side LLM comparison
o3 supports multimodal inputs. Both models have their strengths depending on your specific coding needs.
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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.
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OpenAI
OpenAI o3, released by OpenAI in April 2025, is a large reasoning model that applies extended chain-of-thought processing to deliver improved performance on complex math, science, and coding tasks. It features a 200K token context window and native image understanding, with demonstrated strong results on mathematics and software engineering benchmarks. o3 targets demanding analytical and engineering tasks where deliberate, multi-step reasoning produces significantly better outcomes than direct generation.
3 months newer
o3
OpenAI
2025-04-16
GPT-5 Codex
OpenAI
2025-08
Performance Metrics
Context window and performance specifications
Provider Availability & Performance
Available providers and their performance metrics
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GPT-5 Codex
0 providers
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o3
1 providers
OpenAI
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GPT-5 Codex
Avg Score:0.0%
Providers:0
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o3
Avg Score:0.0%
Providers:1