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GPT-5.3 Codex vs GPT-OSS-20B
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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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.
6 months newer
GPT-OSS-20B
OpenAI
2025-08-05
GPT-5.3 Codex
OpenAI
2026-02
Performance Metrics
Context window and performance specifications
Provider Availability & Performance
Available providers and their performance metrics
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GPT-5.3 Codex
0 providers
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GPT-OSS-20B
1 providers
Hugging Face
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GPT-5.3 Codex
Avg Score:0.0%
Providers:0
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GPT-OSS-20B
Avg Score:0.0%
Providers:1