claudecodex — Run Claude Code with GPT-5.6 using your ChatGPT subscription

claudecodex lets you use Claude Code with OpenAI models — GPT-5.6 (Sol / Terra / Luna) as the engine — billed to your ChatGPT Plus/Pro subscription through a local Codex proxy, without an Anthropic API key or an OpenAI API key.

You keep the Claude Code agent workflow you like (file edits, terminal flow, approvals, MCP servers, skills) but the model answering is GPT-5.6, running on the ChatGPT subscription you already pay for instead of your Anthropic usage.

One-line install. Plain claude stays completely stock.

How it works

claudecodex launches the real Claude Code UI, points it at a local Anthropic-compatible proxy on 127.0.0.1:18765, and the proxy forwards requests to GPT-5.6 via Codex auth on your ChatGPT subscription:

claudecodex
   → claude (real Claude Code UI)
   → local Anthropic-compatible proxy (127.0.0.1:18765)
   → Codex auth via your ChatGPT Plus/Pro subscription
   → GPT-5.6-sol
   → streamed back into Claude Code

Jump to: Install · Usage & model switching · Configuration · vs alternatives · Troubleshooting · FAQ: Claude Code without an Anthropic API key

Demo

(8× speed — watch the full demo video)

---

Why run Claude Code with OpenAI models?

• Claude Code UI + GPT models — the best agentic coding interface, driving OpenAI's strongest coding model (GPT-5.6 Sol at max reasoning effort).
• Uses the ChatGPT subscription you already have — no pay-per-token API bills; requests go through Codex auth on your Plus/Pro plan.
• Zero interference — a thin launcher that execs claude with process-local environment variables. Your normal claude command, login, settings, and Anthropic models are untouched.
• Full 372K context window — configured to GPT-5.6 Sol's real Codex context limit, so the context gauge and auto-compaction are accurate.
• Model switching built in — flip between Sol (best), Terra (mid), and Luna (fast/cheap) per launch or mid-session.

claudecodex is a thin launcher: it starts the proxy if needed, exports the right environment only for that process, then execs claude.

---

Requirements

1. Claude Code — the claude CLI. Install: https://claude.com/claude-code
2. claude-code-proxy — the local Anthropic⇄Codex proxy by @raine. Needs a build that knows the GPT-5.6 models (v0.1.8+; v0.1.17 or newer recommended).
3. A ChatGPT Plus/Pro account, authenticated through the proxy's Codex login. The proxy keeps its own login (it does not reuse the standalone Codex CLI's credentials), so you authenticate it once with claude-code-proxy codex auth login.

This is for personal, local use with your own subscription. Don't expose it as a public API or resell access — routing a ChatGPT subscription through non-official clients is a gray area under OpenAI's terms.

---

Install

1 — install the launcher (one-liner):

curl -fsSL https://raw.githubusercontent.com/karem505/claudecodex/main/install.sh | bash

2 — install the proxy (skip if you already have v0.1.8+):