Comprehensive side-by-side LLM comparison
. Both models have their strengths depending on your specific coding needs.
OpenAI
GPT-5.1 Codex Max, released by OpenAI in November 2025, is an enhanced coding variant from the GPT-5.1 Codex line, designed for more complex software engineering tasks requiring additional reasoning depth. It targets large-scale code generation, automated refactoring, and sophisticated agentic development workflows.
OpenAI
GPT-OSS-120B, released by OpenAI in August 2025, is an open-weight large language model with 120 billion parameters distributed under the Apache 2.0 license. It represents OpenAI's entry into the open-source model space, enabling developers to self-host and fine-tune a GPT-5-generation-class model. GPT-OSS-120B targets research applications, on-premises deployments, and custom fine-tuning workflows requiring a large open-weight base model.
3 months newer

GPT-OSS-120B
OpenAI
2025-08

GPT-5.1 Codex Max
OpenAI
2025-11
Context window and performance specifications
Available providers and their performance metrics
GPT-5.1 Codex Max
GPT-OSS-120B
Hugging Face
GPT-5.1 Codex Max
GPT-OSS-120B
GPT-5.1 Codex Max
GPT-OSS-120B