# GPT-5.3 Codex

> GPT-5.3 Codex on Clonvo: 400K context, $1.75 input and $14.00 output per 1M tokens.

Most advanced agentic coding model combining frontier coding performance with broader reasoning capabilities.

This model is being retired

Requests will be rejected from Apr 1, 2027. Move to a newer model before then.

-   Model id: `openai/gpt-5.3-codex`
-   Provider: OpenAI
-   Released: Feb 24, 2026
-   Context: 400K tokens
-   Max output: 128K tokens

## Pricing

The provider’s list price in USD. Requests on credits are charged exactly this; each response reports its cost in usage.cost.

| Charge | Price | Unit |
| --- | --- | --- |
| Input (prompt) | $1.75 | per 1M tokens |
| Output (completion) | $14.00 | per 1M tokens |
| Cache read | $0.175 | per 1M tokens |
| Web search | $0.01 | per search |

## Capabilities

-   Tools
-   Vision
-   Reasoning
-   Web search

### Reasoning efforts

Values accepted for `reasoning_effort` or `reasoning.effort`:

-   `low`
-   `medium`
-   `high`
-   `xhigh`

## Quick start

Use the OpenAI SDK with Clonvo’s base URL and this model id.

```python
import os
from openai import OpenAI

client = OpenAI(
    base_url="https://api.clonvo.com/v1",
    api_key=os.environ["CLONVO_API_KEY"],
)

completion = client.chat.completions.create(
    model="openai/gpt-5.3-codex",
    messages=[{"role": "user", "content": "Summarise the plot of Hamlet in one sentence."}],
)
print(completion.choices[0].message.content)
```

## Data policy

Requests to this model are sent to OpenAI, whose API terms govern how they handle your data: [OpenAI data policy](https://openai.com/enterprise-privacy/). Clonvo doesn’t store prompts or responses unless your organization turns on retention.

## Bring your own key

From Pay as you go up, a OpenAI key added under Provider keys is used for this model before your credits: $25,000 a month free, then 4% of list price. [How bring-your-own-key works](https://clonvo.com/docs/byok.md).