OpenAI Codex

OpenAI's Capabilities for Code Scenarios and Entry to Development Documentation. Developers can create API Keys, install SDKs to make their first successful calls, and learn about agent construction and multimodal model selection from here.

AI Developer Tools#Programming#OpenAI#API

Updated: 2026-10-26

What is OpenAI Codex?

Codex is OpenAI's product line of coding agents for software development, and the link here points to the technical entry for developers: OpenAI Developer Quick Start Documentation. It explains how to create and export an API Key, install the SDK, make your first API call successfully, and outlines the complete path from model selection to agent construction. Officially, OpenAI API is described as providing a consistent interface for tasks such as text generation, natural language processing, and computer vision, serving as the starting point for developers to access OpenAI's coding capabilities.

Who is it for?

Developers who want to integrate model capabilities into their code workflows themselves, technical decision-makers who want to understand which interfaces OpenAI offers in the fields of code and agents, as well as engineering teams that are preparing to build applications or internal tools based on the OpenAI API; it is also suitable for automation engineers who want to call model capabilities in scripts and CI processes.

Key features

Get Started Quickly

From creating and exporting an API Key to installing the SDK and running your first request, all steps are provided, and you can complete your first call within minutes.

Model Selection Guide

The document differentiates between text and code, reasoning, image and video, real-time and audio, and specialized models, and provides instructions for prompts and reasoning usage to facilitate model selection based on tasks.

Agent Development

Provides Agents API, Agents SDK and ChatKit for building tool-augmented agents and expanding model capabilities into task-executable workflows.

Tools & Multimodality

Covers capabilities such as extending tools for models, streaming responses, building real-time applications, and image and file analysis; streaming responses are suitable for long text and real-time interaction scenarios, while image and file analysis enable models to process multimodal inputs.

Multi-language SDK and CLI

Supports integration with mainstream languages and provides command-line tools to meet the needs of different tech stacks and automation scenarios.

How to use OpenAI Codex

Start with quickly getting a call up and running to understand the request and response structure, then select a model based on the task type: for daily code generation and completion, look at the text and code directions.
for complex reasoning tasks, use reasoning models.
for real-time interaction needs, check the real-time and audio directions.
When building an agent, it is recommended to start with the Agents SDK.
First, create a small agent with a single tool to verify the process, then expand it step by step.
before team access, agree on the key management and quota allocation methods.

Things to know

This link leads to the documentation site rather than the product homepage. To directly experience the coding agent, it is recommended to go to the independent entry of Codex. Using the OpenAI API requires registering an account and pre-paying or binding a payment method, which will result in real token consumption; for use in China, you need to solve the network and payment issues by yourself. Be sure to keep your API Key safe to avoid fees being incurred due to theft by others after leakage; before accessing, confirm the model's rate limiting strategy and billing standards, and it is recommended to enable usage monitoring and budget alerts to avoid unexpected overspending.