Comprehensive side-by-side LLM comparison
o3 Pro supports multimodal inputs. Both models have their strengths depending on your specific coding needs.
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.
OpenAI
OpenAI o3-pro, released by OpenAI in June 2025, is an extended reasoning model from the o3 family that applies more compute per response to deliver deeper, more thorough answers on complex problems. It features a 200K token context window, 100K maximum output tokens, and vision capabilities. o3-pro targets research-grade reasoning tasks, extended coding sessions, and applications where accuracy on difficult problems justifies higher inference cost and latency.
1 month newer

o3 Pro
OpenAI
2025-06-10

GPT-5 Codex
OpenAI
2025-08
Context window and performance specifications
Available providers and their performance metrics
GPT-5 Codex
o3 Pro
OpenAI
GPT-5 Codex
o3 Pro
GPT-5 Codex
o3 Pro