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GPT-5.3 Codex vs Llama-3.1 Nemotron Ultra 253B
Comprehensive side-by-side LLM comparison
. 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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NVIDIA
Llama-3.1-Nemotron-Ultra-253B-v1 is a 253-billion-parameter model from NVIDIA, derived from Meta's Llama 3.1 405B using neural architecture search (NAS) compression combined with NVIDIA's Nemotron post-training pipeline, which recovers and exceeds the base model's capability after structural compression. Released in April 2025, it supports toggling between a standard instruction mode and an extended reasoning mode via system prompt, allowing the same model to handle both rapid responses and deliberate chain-of-thought tasks. It is the flagship of the Nemotron family, available open-weight on HuggingFace and through NVIDIA NIM for enterprise inference.
10 months newer
Llama-3.1 Nemotron Ultra 253B
NVIDIA
2025-04-07
GPT-5.3 Codex
OpenAI
2026-02
Provider Availability & Performance
Available providers and their performance metrics
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GPT-5.3 Codex
0 providers
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Llama-3.1 Nemotron Ultra 253B
0 providers
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GPT-5.3 Codex
Avg Score:0.0%
Providers:0
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Llama-3.1 Nemotron Ultra 253B
Avg Score:0.0%
Providers:0