What are Claude Code and Codex?
Claude Code is an AI coding agent from Anthropic that runs as a command-line tool, started with the claude command. Codex is an AI coding agent from OpenAI that runs as a command-line tool, started with the codex command. This page compares the two CLIs.
Both belong to the same category: AI coding agents that work in an interactive terminal session inside your project. You describe a task in plain language; the agent reads the code, proposes and makes edits, runs commands such as your tests, and reports back. Tallos has setup pages for each: Claude Code and Codex.
How do Claude Code and Codex compare?
On the stable facts — who makes them, how you install them, how you sign in — they are close cousins. The table sticks to those facts on purpose.
| Claude Code | Codex | |
|---|---|---|
| Made by | Anthropic | OpenAI |
| Form | CLI in your terminal (claude) | CLI in your terminal (codex) |
| Install on macOS | npm @anthropic-ai/claude-code or Homebrew cask claude-code | npm @openai/codex or Homebrew cask codex |
| Install on Windows | npm @anthropic-ai/claude-code | npm @openai/codex |
| Sign in | claude auth login | codex login |
| Use an API key | ANTHROPIC_API_KEY environment variable | codex login --with-api-key |
| Models | Anthropic's models | OpenAI's models |
| Project instructions file | CLAUDE.md | AGENTS.md |
| Reads code, edits files, runs commands | Yes | Yes |
| Opens in the Tallos chat view | Yes, by default | Yes, by default |
| Usage readout and account switching in Tallos | Yes | Yes |
What do Claude Code and Codex have in common?
Most of the day-to-day workflow is the same. That is why comparing them on your own tasks is easy.
- Terminal-first. Both are interactive CLIs that start in the folder you run them from.
- Real edits. Both change files on disk and run shell commands, so both benefit from an isolated working copy per task.
- Approvals. Both let you control how much they may do without asking. Match that setting to how much you trust the task.
- Project instructions. Both read a Markdown file of project conventions from the repo, so you can give each the same house rules.
- Your account. Both work with a vendor account sign-in or an API key you already have.
Which is better, Claude Code or Codex?
Neither is better in general. Results depend on your language, your codebase, the task, the prompt and the model settings — and both tools ship updates often. Any page that crowns a winner today can be wrong after the next release, so we don't.
What does differ is concrete: the vendor, the model family behind each agent, the account you sign in with, default behaviors, the look of each terminal interface, and small workflow conventions. Those are good reasons to prefer one for a given team. None of them tells you which will do better on your next ticket. Only running both does.
Do I have to choose between Claude Code and Codex?
No. Tallos runs Claude Code and Codex at the same time on the same repository, each in its own workspace with its own branch, so they never touch each other's files. Both use the subscriptions or API keys you already have; Tallos does not resell model access.
The Connections page installs each CLI with the vendor's verified command, opens its sign-in or stores its API key in secure storage, and lists its models. Step by step: connect your agents.
Run Claude Code and Codex side by side on your own repo.
How do I decide between Claude Code and Codex for my repo?
Run the same real task on both and compare the diffs. A handful of tasks from your own backlog will tell you more than any generic benchmark.
- 1
Pick a real task
Take a ticket from your backlog, not a toy problem. Include how to verify it, such as which tests must pass.
- 2
Create two workspaces
Start both from the same branch so the agents see identical code.
- 3
Start one agent in each
Claude Code in the first workspace, Codex in the second. Paste the same prompt into both.
- 4
Compare the diffs
Check correctness, scope (did it touch only what it needed?), readability and whether the tests pass.
- 5
Send review notes to both
Comment on lines and send the notes back. How each agent revises is part of the comparison.
- 6
Repeat on different kinds of tasks
A bug fix, a refactor and a new feature can each point to a different agent.
Or let a squad run the comparison. The best-of-three squad uses the template "3 attempts, pick the best": set one attempt to Claude Code and another to Codex, and the leader compares the results and marks one as Recommended. Nothing merges without your approval.
Frequently asked questions
Is Claude Code better than Codex?
There is no general answer. Results depend on your codebase, the task and the model settings, and both tools change often, so the reliable way to decide is to run the same task on both and compare the diffs.
Can I use Claude Code and Codex at the same time?
Yes. In Tallos each agent runs in its own workspace on its own branch, so both can work on the same repository at once without overwriting each other's files.
Do I need two subscriptions to use both?
Each agent signs in with its own vendor: Claude Code with Anthropic, Codex with OpenAI, using an account or an API key. Tallos uses the accounts you already have and does not sell model access.
Do Claude Code and Codex work on Windows?
Both can be installed on Windows with npm, and Tallos runs on Windows 10 or later. On macOS 13 or later you can also install either one with Homebrew.
Can a squad mix Claude Code and Codex?
Yes. Each squad member picks its own agent and model, so Claude Code can build while Codex reviews, or each can take one attempt in a best-of-N run.
How do I install Claude Code and Codex in Tallos?
Open Settings → Connections. Each agent has a card to install it with the vendor's verified command, sign in or save an API key, and see its models.
What about Gemini CLI?
Gemini CLI, from Google, is a third agent in the same category. See the three-way comparison of Claude Code, Codex and Gemini CLI.
