Comprehensive side-by-side LLM comparison
. 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
GPT-OSS-20B is an open-weight large language model with 20 billion parameters from OpenAI's open-source model initiative. It targets deployments requiring a smaller, efficient model that can run on consumer or mid-tier hardware while maintaining strong reasoning and coding capabilities relative to its size.
5 months newer

GPT-OSS-20B
OpenAI
2025-08-05

GPT-5.2 Codex
OpenAI
2026-01-14
Context window and performance specifications
Available providers and their performance metrics
GPT-5.2 Codex
GPT-OSS-20B
Hugging Face
GPT-5.2 Codex
GPT-OSS-20B
GPT-5.2 Codex
GPT-OSS-20B