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GPT OSS 20B vs GPT-5 Codex
Comprehensive side-by-side LLM comparison
GPT OSS 20B is available on 4 providers. Both models have their strengths depending on your specific coding needs.
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OpenAI
GPT-OSS 20B was created as a smaller open-source variant, designed to balance capability with accessibility for researchers and developers. Built with 20 billion parameters, it provides a more approachable entry point for those seeking to work with open-source language models while benefiting from OpenAI's architectural insights.
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OpenAI
GPT-5 Codex was developed as a specialized variant of GPT-5 optimized for programming and software development tasks. Built to understand and generate code across multiple programming languages, it serves developers with enhanced capabilities for code completion, debugging, translation, and explanation of complex codebases.
1 month newer
GPT OSS 20B
OpenAI
2025-08-05
GPT-5 Codex
OpenAI
2025-09-15
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Performance Metrics
Context window and performance specifications
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Knowledge Cutoff
Training data recency comparison
GPT-5 Codex
2024-09-30
More recent knowledge cutoff means awareness of newer technologies and frameworks
Provider Availability & Performance
Available providers and their performance metrics
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GPT OSS 20B
4 providers
Groq
Throughput: 1000 tok/s
Latency: 0.38ms
Novita
OpenAI
Throughput: 115 tok/s
Latency: 5.2ms
ZeroEval
Throughput: 1000 tok/s
Latency: 0.38ms
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GPT OSS 20B
Avg Score:0.0%
Providers:4
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GPT-5 Codex
Avg Score:0.0%
Providers:0