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GPT-5.3 Codex vs o1
Comprehensive side-by-side LLM comparison
o1 supports multimodal inputs. Both models have their strengths depending on your specific coding needs.
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OpenAI
GPT-5.3 Codex, released by OpenAI in February 2026, is a coding-specialized large language model from the GPT-5.3 family. It targets software engineering workflows including automated code generation, test writing, and agentic multi-file editing, built on the incremental improvements of the GPT-5.3 generation.
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OpenAI
OpenAI o1, released by OpenAI in December 2024, is a reasoning-focused large language model that applies extended chain-of-thought processing before generating responses. It features a 200K token context window and native image understanding, demonstrating strong performance on STEM benchmarks requiring multi-step reasoning. o1 targets mathematics, science, and coding tasks where careful deliberation over the problem produces more accurate outputs than direct generation.
1 year newer
o1
OpenAI
2024-12-05
GPT-5.3 Codex
OpenAI
2026-02
Performance Metrics
Context window and performance specifications
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Knowledge Cutoff
Training data recency comparison
o1
2023-10
More recent knowledge cutoff means awareness of newer technologies and frameworks
Provider Availability & Performance
Available providers and their performance metrics
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GPT-5.3 Codex
0 providers
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o1
1 providers
OpenAI
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GPT-5.3 Codex
Avg Score:0.0%
Providers:0
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o1
Avg Score:0.0%
Providers:1