TL;DR: 5 minutes to point Codex CLI at CodeGateway, call GPT-5.3 Codex through the OpenAI Responses API, pay as you go without an overseas credit card.
We tested this flow on our own machines and recommend running through all 5 steps before customizing — every step ships with a copy-paste command.
This tutorial walks through using Codex CLI with CodeGateway as the access layer for the GPT-5.3 Codex model. Codex CLI is OpenAI's command-line coding assistant; it speaks the OpenAI Responses API protocol. CodeGateway exposes a /v1/responses endpoint that implements the same protocol contract, so Codex CLI works with CodeGateway by setting the base URL accordingly.
Reference: OpenAI Codex CLI repo | Responses API docs for protocol parameters and endpoint definitions.
1. Prerequisites
Sign up for CodeGateway (get $2 of free credit) and generate an API key in the Dashboard. Codex CLI needs Node.js 18+.
2. Install Codex CLI
npm install -g @openai/codex