Codex OAuth Backend Example

codex-oauth-min.js

#!/usr/bin/env node
// Minimal REST call to the Codex backend API using a local OAuth token.

import fs from "fs";
import os from "os";
import path from "path";

const authFile = process.env.CODEX_AUTH_FILE || path.join(os.homedir(), ".codex", "auth.json");
const auth = JSON.parse(fs.readFileSync(authFile, "utf8"));
const token = auth.access_token || auth.tokens?.access_token;
if (!token) throw new Error("auth file missing access_token");

const url = process.env.CODEX_URL || "https://chatgpt.com/backend-api/codex/responses";
const model = process.env.CODEX_MODEL || "gpt-5.3-codex";

const res = await fetch(url, {
  method: "POST",
  headers: {
    "Content-Type": "application/json",
    "Authorization": `Bearer ${token}`,
  },
  body: JSON.stringify({
    model,
    instructions: "",
    stream: true,
    store: false,
    reasoning: { effort: "xhigh" },
    input: [
      {
        type: "message",
        role: "user",
        content: [{ type: "input_text", text: "Hello from the minimal example." }],
      },
    ],
  }),
});

if (!res.ok) {
  console.error(`HTTP ${res.status}`);
  console.error(await res.text());
  process.exit(1);
}