gpt-oss (OpenAI) vs Codex (OpenAI)
Which one should you pick? Here's the full breakdown.
gpt-oss (OpenAI)
OpenAI's FIRST open-weight models -- gpt-oss-120b (single 80GB GPU, near parity with o4-mini on reasoning) and gpt-oss-20b (runs on 16GB edge devices). Apache 2.0. Launched 2025-08-05. gpt-oss-safeguard ships in 2026 as the safety-tuned variant
Codex (OpenAI)
OpenAI's cloud-based coding agent -- runs parallel tasks, proposes PRs, and lives inside ChatGPT
Powered by GPT-5.3-Codex / GPT-5.4
| Category | gpt-oss (OpenAI) | Codex (OpenAI) |
|---|---|---|
| Ease of Use | 7.0 | 8.0 |
| Output Quality | 8.5 | 8.0 |
| Value | 10.0 | 8.0 |
| Features | 7.0 | 9.0 |
| Overall | 8.1 | 8.3 |
Pricing Comparison
| Feature | gpt-oss (OpenAI) | Codex (OpenAI) |
|---|---|---|
| Free Tier | Yes | Yes |
| Starting Price | $0 | $0 |
Benchmark Head-to-Head
GPT-5.3-Codex benchmarks — gpt-oss (OpenAI) has no published benchmarks
| Benchmark | Description | Score |
|---|---|---|
| SWE-bench | Real GitHub issue fixing | 72% |
| HumanEval | Python code generation | 95% |
Which Should You Pick?
Pick gpt-oss (OpenAI) if...
- ✓Better value for money (10/10)
Developers who want OpenAI-brand open-weight reasoning models for self-hosting or fine-tuning. Particularly good for single-GPU deployments (gpt-oss-120b on one 80GB card) or edge-device reasoning (gpt-oss-20b on 16GB consumer GPUs / Apple Silicon). Also good as a reliable baseline when comparing newer open-weight releases.
Visit gpt-oss (OpenAI)Pick Codex (OpenAI) if...
- ✓Easier to use (8 vs 7)
- ✓More features (9 vs 7)
Developers already paying for ChatGPT Plus who want a coding agent at no extra cost. Especially good for parallel task execution -- assign multiple bug fixes or feature branches and let Codex work them simultaneously.
Visit Codex (OpenAI)Our Verdict
gpt-oss (OpenAI) and Codex (OpenAI) are extremely close overall. Your choice comes down to specific needs -- gpt-oss (OpenAI) is better for developers who want openai-brand open-weight reasoning models for self-hosting or fine-tuning, while Codex (OpenAI) works best for developers already paying for chatgpt plus who want a coding agent at no extra cost.