Comprehensive side-by-side LLM comparison
o3 supports multimodal inputs. Both models have their strengths depending on your specific coding needs.
OpenAI
GPT-5.2 Codex is a coding-specialized variant from the GPT-5.2 family, designed for software engineering workflows including automated code generation, multi-file editing, and agentic development. It builds on GPT-5.2's improved instruction following and long-context capabilities, with optimizations specifically targeting programming tasks and agentic software workflows.
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.
9 months newer

o3
OpenAI
2025-04-16

GPT-5.2 Codex
OpenAI
2026-01-14
Context window and performance specifications
Available providers and their performance metrics
GPT-5.2 Codex
o3
OpenAI
GPT-5.2 Codex
o3
GPT-5.2 Codex
o3