GPT-5.3 Codex

OpenAI's most capable agentic coding model to date.

Agentic CodingReasoning ControlLong Horizon Tasks

Context Window

400,000

GPT-5.3 Codex

Max Output

128,000

1M tokens

Input

$1.75

Output

$14

Model Codegpt-5.3-codex

Playground

Model Code

gpt-5.3-codex

Enter your prompt here...

Output

No output yet

Pricing

Plan	Context Window	Max Output	Input	Output	Cache Write	Cache Read
GPT-5.3 Codex	400,000	128,000	$1.75	$14	-	$0.175

Official OpenAI pricing for GPT-5.3 Codex.

Cached input pricing applies to reused prompt tokens.

Cache read or cached input pricing applies to reused prompt tokens.

README

GPT-5.3 Codex is OpenAI's coding-specialized model for Codex-like environments, optimized for long-horizon, agentic software tasks with stronger reasoning controls and coding-oriented reliability.

OpenAI describes GPT-5.3-Codex as its most capable agentic coding model to date.
It is optimized for coding tasks in Codex or similar environments, with support for `low`, `medium`, `high`, and `xhigh` reasoning effort settings.
This model is the best fit for long-running software tasks, agentic code workflows, and products that need a model specialized for implementation rather than general chat.

API

Use the API docs for request format, parameters, and integration details.

OpenAI's most capable agentic coding model to date.

Model Code

gpt-5.3-codex

View API Docs

API

Endpoint

POST /v1/responses

Authentication

Authorization: Bearer YOUR_REACH_API_KEY
Content-Type: application/json

Example

curl -X POST "https://direct.reachapi.ai/v1/responses" \
  -H "Authorization: Bearer YOUR_REACH_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "YOUR_MODEL_ID",
    "input": "Introduce ReachAPI in one sentence.",
    "temperature": 0.2
  }'

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