Codex model on the GPT-5.3 base, optimized for agentic coding harnesses and served via the OpenAI Responses API. 400K token context window, 128K max output tokens, cached inputs at a 90% discount.
Test this model instantly in the Console Playground โ no code required
Copy usage instructions for Claude, ChatGPT, or other AI
| Token Type | Credits | USD Equivalent |
|---|---|---|
| Input Tokens | 3,252 | $2.17 |
| Output Tokens | 26,012 | $17.34 |
| Cached Tokens | 325.15 | $0.22 |
* 1,500 credits โ $1 (actual charges may vary based on usage)
curl -X POST "https://api.core.today/llm/openai/v1/responses" \
-H "Content-Type: application/json" \
-H "Authorization: Bearer cdt_your_api_key" \
-d '{
"model": "gpt-5.3-codex",
"input": "Diagnose why this async job queue occasionally drops tasks under load, then propose and implement a fix:\n\n<code snippet>",
"max_output_tokens": 6000
}'| Parameter | Type | Required | Default | Description |
|---|---|---|---|---|
model | string | Yes | gpt-5.3-codex | Model identifier |
input | string | array | Yes | - | Responses API input: a plain string or an array of input items (messages, tool results) |
instructions | string | No | - | System-level instructions for the run |
max_output_tokens | integer | No | - | Maximum tokens in the response, including internal reasoning tokens (Responses API field; not max_tokens) |
stream | boolean | No | false | Enable Server-Sent Events streaming |
Responses API request using GPT-5.3 Codex
curl -X POST "https://api.core.today/llm/openai/v1/responses" \
-H "Content-Type: application/json" \
-H "Authorization: Bearer cdt_your_api_key" \
-d '{
"model": "gpt-5.3-codex",
"input": "Diagnose why this async job queue occasionally drops tasks under load, then propose and implement a fix:\n\n<code snippet>",
"max_output_tokens": 6000
}'POST /llm/openai/v1/responses