How to Use Claude Code and Codex Together (Stop Choosing)

You're hamstringing yourself if you're trying to choose between Claude Code or Codex. The right play is running both in the same project, having them check each other's work, and treating yourself as tool-agnostic instead of brand-loyal to OpenAI or Anthropic. Here's exactly how I set it up — including pricing, the desktop app walkthrough, and the dual-model review loop that catches bugs neither tool spots on its own.

Claude Code has owned the AI coding discourse for months. The reason was simple: the gap between Claude Code and the second-best option was huge. Codex has quietly closed that gap. GPT 5.5 is arguably better than Opus 4.7, OpenAI's pro plan has more generous usage limits than Anthropic's Max plans, and the Codex desktop app is a legitimately good product on its own.

This is not a "Codex is better" post. It's a "you have options now" post — and the smartest move is using both.

Why Should You Use Both Claude Code and Codex?

The Venn diagram of Codex and Claude Code is basically a circle — about 99% overlap. Learning one means you can learn the other in an afternoon. The benefit of running both isn't redundancy. It's adversarial review.

When one model writes a plan, the other can poke holes in it. When one model ships a feature, the other can audit the diff for bugs. In my last demo, Claude Code found 20 real bugs in a first-pass build that Codex shipped — bugs Codex hadn't caught in its own review. The compound interest of two models reviewing each other across an entire project pays for itself in tokens saved on rework.

There's also the loyalty trap. Most people think they're tool-agnostic — "oh, I'd switch to whatever's best." In reality, they get used to one tool, get tribal about the company behind it, and stop testing the alternative. You owe these companies zero loyalty. The minute one starts trailing, switch. The minute one pulls ahead, lean in. Running both keeps you honest.

How Much Does Codex Cost vs. Claude Code?

By and large, OpenAI gives you more bang for your buck across the board. Token-cost comparisons aren't apples-to-apples — GPT 5.5 costs about the same per million tokens as Opus, but it uses fewer tokens, so total spend trends lower. Usage limits depend on time of day and a few other factors. Here's the cleanest framing:

• GPT 5.5 — available on the $20 plan and up. Solid model on its own.
• GPT 5.5 Pro — only on the $100 or $200 pro plan. Beats some benchmarks where the basic model can't.
• OpenAI's pro plans give more generous 5-hour limits than Anthropic's Max plans, even after Anthropic's recent doubling. Anthropic did NOT double the weekly limits, by the way.

If you're already paying $200/month for Claude Max and wondering whether you also need to drop $100/month on OpenAI Pro, my advice: start at $20/month, get your feet wet, see how you use it. No reason to commit to the higher tier before you know if Codex fits your workflow. You can always upgrade.

For reference, I run the $100 OpenAI Pro plan alongside the Anthropic Max plans. That's the setup I'd recommend if you're serious about going dual-tool.

How Do You Install Codex and Run Claude Code Inside It?

Go to openai.com/codex and run the installer. Setup takes about two seconds. When you open the desktop app, you'll see a chat window, a project sidebar, and a top toolbar. The whole UI is intentionally ChatGPT-coded — very intuitive if you've used any OpenAI product.

The trick that makes the dual-tool workflow easy is the built-in terminal. Top right of the app, click "Toggle terminal." A terminal opens inside the Codex app, scoped to whatever project you're working in. From there, run claude and you've got Claude Code running inside Codex. Same project directory, same file system, both agents seeing the same code.

There's a Codex CLI too, but in my experience the desktop app is the better path. You get quality-of-life features the CLI doesn't have:

• In-app browser — preview your dev server side-by-side with the chat. No tab-switching.
• Pets — a small visual indicator that floats on top of any window and tells you when Codex is working vs. ready for input. Sounds dumb. Actually useful for not losing time when you tab away mid-task.
• Diff viewer — every file change is reviewable in a clean diff UI inside the app.
• Annotation mode — highlight elements in the in-app browser and leave inline comments for the agent to act on.

How Does the Codex Desktop App Compare to Claude Code?

The two are functionally near-identical. Different UI, same primitives: prompts, plan mode, permissions, skills, automations, MCPs. If you're coming from Claude Code, almost everything has a one-to-one analog.

Here's the mapping I've found most useful:

• CLAUDE.md → AGENTS.md — Codex's version of the project-level system prompt is named AGENTS.md. Same idea, different filename. If you've already got a CLAUDE.md Codex will respect it too via skill imports, but AGENTS.md is the canonical file for the platform.
• Routines → Automations — recurring scheduled tasks. Codex has a default set built in and you can create new ones with natural language or by clicking through the UI.
• Skills → Skills — same concept. The first time you open Codex, it'll detect skills you've installed for Claude Code or Open Code and offer one-click import. So your skill library moves with you.
• Plugins — Codex's MCP-bundle equivalent. One-click installs for things like Supabase, Chrome, spreadsheets, presentations. Each plugin ships an MCP plus the matching skills.
• Projects + chats → folders + terminals — the project sidebar is where you scope work to a folder. Each chat inside a project is roughly equivalent to a separate terminal session. You can fork chats, open multiple chats per project, pin them, rename them. Cleaner mental model than juggling terminal windows.

One context window difference worth noting

GPT 5.5 Pro has a 258K context window. Claude Code is at 1M. On paper that sounds like a big gap. In practice, most people have no idea how to manage their own context anyway — they let it run raw until things break. A 258K window forces discipline. And starting a new chat inside Codex is the equivalent of /clear in Claude Code, just visually obvious instead of buried in a slash command.

Codex auto-compacts when you hit 258K, which has its own issues if you keep compacting the same conversation. The fix is the same as in Claude Code: start a fresh chat instead of running the old one through compaction five times.

What Does the Dual-Tool Workflow Actually Look Like?

The simplest version: plan in one tool, build in the other, have each one review the other's work. Here's the loop I ran in a recent demo to build a local AI trend planner web app.

1. Drop the prompt into Codex in plan mode. Codex asks clarifying questions, comes back with a plan: greenfield Next.js + TypeScript + SQLite app with a dashboard, RSS-based ingestion, local AI generation via Ollama, mini Kanban board.
2. Copy the plan into Claude Code. Ask: "Codex came up with this plan. What's missing?" Claude Code returns gaps, soft concerns, and nitpicks.
3. Paste Claude's feedback back into Codex. Codex reads it, agrees with the main critique, revises the plan to add trend-signal ranking and competitor saturation checks instead of just ingestion.
4. Execute the build in Codex. ~23 minutes for the first pass. Code runs end-to-end.
5. Review pass: ask Claude Code to audit the diff. Claude found 20 real bugs Codex hadn't flagged in its own review — timestamp issues, competitor self-warning logic, navigation glitches.
6. Hand specific bugs back to either tool to fix. I dropped a few directly into Claude Code, others into Codex.

Neither tool would have shipped a working app on its own without iteration. But the dual-review pattern catches bugs at planning time and at code-review time, which is where compound savings show up. Yes, you burn extra tokens running two models. You save more by not chasing bugs through three rebuilds.

This pattern works in either direction — Claude Code can build, Codex can review. There's also a Codex plugin for Claude Code that ships an adversarial-review skill specifically for this loop.

How Do You Stay Tool-Agnostic Long-Term?

The point isn't "use Codex and Claude Code right now." The point is to never get tribal about either one. Most people who claim they'd switch to whatever's best never actually do. They get habit-locked, they get emotionally invested in one company's narrative, and they stop testing.

The forecasted reality is that model leadership keeps trading hands. Six months ago Anthropic was clearly ahead. Today GPT 5.5 is arguably ahead. In six months it could be Gemini, or whatever Anthropic ships next. The frontier is converging — they're all becoming really good, fast. That means "which model is best" is going to be a question with a different answer every quarter, and the answer is going to matter less because all of them will handle 99% of what an average user throws at them.

The play is:

• Run multiple tools side by side, even if it costs more in subscriptions.
• Bias toward whichever one is leading right now for the specific task at hand.
• Switch fast. The cost of switching is low (skills auto-port between tools). The cost of being habit-locked to a worse tool for six months is high.
• Don't get emotionally attached to a company. They'll trade leadership. You won't.

The walled-garden risk doesn't really exist here yet. OpenAI shipped a Claude Code plugin. Codex auto-imports skills from Claude Code. Anthropic and OpenAI are both quietly making it easier to use both in tandem rather than locking you in. Take advantage of that while it lasts.

Frequently Asked Questions

Is Codex actually better than Claude Code now?

Not strictly better — comparable, with different strengths. GPT 5.5 (and especially GPT 5.5 Pro) holds its own against Opus 4.7 on many tasks. Claude Code still tends to do better on front-end design and aesthetics in my experience. Codex tends to be slightly slower on heavy tool-call workflows but faster in pure chat. The honest answer: it depends on the specific task, and that's exactly why running both is the move.

Do I need GPT 5.5 Pro, or is regular GPT 5.5 enough?

If you're brand new to Codex, start with the $20/month plan and use regular GPT 5.5. It's a real model — not a stripped-down version. Upgrade to Pro ($100/month) only after you've used Codex enough to know whether the extra capability is worth it for your workflow. The Pro tier mostly matters for harder problems where the extra reasoning depth shows up.

Can I import my Claude Code skills into Codex?

Yes — and it's one click. The first time you open Codex, it detects skills installed for Claude Code (or Open Code) and offers to import them. No copying files, no rebuilding your skill library. This is one of the main reasons switching between the tools is so cheap.

What's the difference between CLAUDE.md and AGENTS.md?

Same concept, different filename. AGENTS.md is Codex's version of CLAUDE.md — a project-level system prompt that gets appended to every prompt inside that directory. If you've got a CLAUDE.md already, you can either rename a copy to AGENTS.md or let Codex's skill import handle it. The conventions inside the file (folder structure, naming rules, routing logic) carry over unchanged.

Can I just use the Codex CLI instead of the desktop app?

You can, but you'll miss the parts that make the dual-tool workflow easy: the built-in terminal (where you run claude alongside Codex), the in-app browser, the diff viewer, and the annotation mode. The desktop app is doing the hard work of giving you a unified workspace. The CLI alone is fine if you want raw Codex, but for using Codex and Claude Code together, the desktop app is the better path.

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If you want to go deeper into running Claude Code and Codex in tandem, join the free Chase AI community for templates, prompts, and live breakdowns. And if you're serious about building with AI, check out the paid community, Chase AI+, for hands-on guidance — including the full Codex Masterclass alongside the Claude Code Masterclass.