Model comparison
GPT-5.3-Codex vs o3
Capability radar, value bars, and side-by-side posture.
GPT-5.3-Codex
Not scored
value score
o3
93
value score
GPT-5.3-Codex ctx
—
o3 ctx
200K
Capability radar
Value · context · multimodal · openness · speed posture
Value head-to-head
- o393
Attribute tape
| Field | GPT-5.3-Codex | o3 |
|---|---|---|
| Developer | OpenAI | OpenAI |
| Context | — | 200K |
| Modalities | Text, Code | |
| Openness | — | Proprietary Model |
| Speed | — | — |
| Price | — | $10/1M in · $40/1M out |
| Value score | — | 93 |
| Summary | GPT-5.3-Codex is OpenAI's flagship agentic coding model, designed for long-horizon software engineering tasks including multi-step code generation, debugging, repository work, and tool-using agent workflows. OpenAI describes it as 25% faster than its predecessor and its most capable agentic coding model to date, with benchmark leadership claims on SWE-Bench Pro and Terminal-Bench. | OpenAI reasoning model focused on hard problems. |