As of: 2026-11-13 13:49 CET.
Researched and written by AI agents (Claude Opus 5.5 in Claude Code), with a human editor. How we work: https://postcutoff.com/about/
Canonical page: https://postcutoff.com/m/gpt-5-3-codex/

# GPT-5.3-Codex

OpenAI, GPT-5 Codex family. Status: deprecated. Type: code model. Released: 2026-02-05. Training cutoff: 2025-08.

## How to call it

| Provider | Model id | Endpoint | Docs |
|---|---|---|---|
| OpenAI API | `gpt-5.3-codex` | https://api.openai.com/v1/responses | https://developers.openai.com/api/docs/models/gpt-5.3-codex |
| Azure OpenAI (Microsoft Foundry) | `gpt-5.3-codex` |  | https://learn.microsoft.com/en-us/azure/foundry/foundry-models/concepts/models-sold-directly-by-azure |
| OpenRouter | `openai/gpt-5.3-codex` |  | https://openrouter.ai/openai/gpt-5.3-codex |
| Codex (ChatGPT) |  |  | https://chatgpt.com/codex |

## Pricing

- Input: $1.75 per 1M tokens
- Cached input: $0.175 per 1M tokens
- Output: $14 per 1M tokens
- Unit as published: per 1M tokens (USD), standard tier
- Source: https://developers.openai.com/api/docs/pricing
- Last checked: 2026-10-15

## Specs

- Input: text, image
- Output: text
- Context window: 400,000 tokens
- Max output: 128,000 tokens
- Open weights: no
- Licence: proprietary

## Where it stands

- Newer code models in the registry since its release: 5:
  - Recursive Flint (2026-10-21) https://postcutoff.com/m/recursive-flint/
  - Mellum2.1 12B-A2.5B Thinking (2026-10-08) https://postcutoff.com/m/mellum2-1/
  - Leanstral 1.5 (2026-07-02) https://postcutoff.com/m/leanstral-1-5/
  - Kimi K2.7 Code (2026-06) https://postcutoff.com/m/kimi-k2-7-code/
  - Grok Build 0.1 (2026-05) https://postcutoff.com/m/grok-build-0-1/
- Closed weights; access is hosted only.

## What stands out

- Agentic coding specialist: Codex-tuned GPT-5.3 for long-running software engineering (Codex app/CLI/IDE and API). Source: https://developers.openai.com/api/docs/models/gpt-5.3-codex
- Responses-only: Available only through the Responses API; effort low/medium/high/xhigh. Source: https://developers.openai.com/api/docs/models/gpt-5.3-codex

## Notes

Latest codex-specific API id on the pricing page. Released in Codex Feb 5 2026; API access followed later (Azure version 2026-02-24). GPT-6 Sol is now positioned for coding. Deprecated 2026-10-01 (with gpt-5.1 and gpt-5.4-nano): removal from the API on Apr 1 2027, replacement gpt-6-sol (https://developers.openai.com/api/docs/deprecations).

```bash
curl https://api.openai.com/v1/responses \
 -H "Authorization: Bearer $OPENAI_API_KEY" -H "Content-Type: application/json" \
 -d '{"model":"gpt-5.3-codex","input":"Hello"}'
```

Sources:
- https://developers.openai.com/api/docs/models/gpt-5.3-codex
- https://developers.openai.com/api/docs/pricing
- Models overview: https://developers.openai.com/api/docs/models

Model page: https://postcutoff.com/m/gpt-5-3-codex/