The Codex CLI runs on your phone through Cosyra for iPhone or Cosyra for Android. The CLI itself runs in a cloud Linux workspace, where it is already installed. Your phone is the terminal.
This page is about the command line: starting it, the sign-in that works from a mobile device, and the commands worth knowing. If you only want the quickest way in, read Codex on your phone. The screenshots are from the Cosyra 2.8.5 iPhone app, taken in October 2026.
What you need
- The Cosyra app. Core is $20 a month and Pro is $30. Eligible new users can start a 7-day free trial in the App Store app. Pricing has the details.
- A ChatGPT plan or an OpenAI API key. Codex says usage is included with Plus, Pro, Business and Enterprise plans.
Run the Codex CLI on a mobile device
Step 1
Open a terminal in Cosyra
On Terminals, tap New and choose New terminal. You get a shell in your workspace home folder.
The Codex shortcut does this and starts the CLI in one tap. Use it when you do not need a shell first.
Step 2
Start the Codex CLI
Type the command and press return:
codexThere is nothing to install. On first run the CLI asks how you want to sign in:
- Sign in with ChatGPT
- Sign in with Device Code
- Provide your own API key
Step 3
Sign in with a device code
Move down to Sign in with Device Code with the arrow keys in the toolbar and press return. The CLI prints a link and a one-time code.
Tap the link, sign in to ChatGPT in the browser and enter the code. It expires after 15 minutes. Back in Cosyra the CLI moves on by itself.
This is the sign-in to pick on a phone. The first option expects a browser on the same machine as the CLI, and here the CLI is in the cloud.
Step 4
Or use an API key
Choose Provide your own API key to pay for what you use through your OpenAI account. Paste the key when the CLI asks for it. It is stored in your workspace, not on the phone.
Step 5
Run Codex in a project
Change into a repository and start the CLI there:
git clone https://github.com/you/your-repo.git
cd your-repo
codexYou can pass the prompt on the command line, which saves typing in the interactive screen:
codex "explain what this repo does"Commands worth knowing on a phone
| Command | What it does |
|---|---|
| codex --version | Shows the installed release. |
| codex "prompt" | Opens the CLI with that prompt already sent. |
| codex exec "prompt" | Runs one task without the interactive screen and exits. |
| codex resume | Picks up an earlier session. |
| /model | Inside the CLI, switches the model. |
| /status | Inside the CLI, shows the account and session details. |
An AGENTS.md file in the repository tells Codex how the project is
built and tested. It is worth adding before a long task, because Codex reads it
at the start of every session.
The keys the CLI needs
The Codex CLI is driven with Esc, Ctrl and the arrow keys. Cosyra puts those in a toolbar above the keyboard, with Tab, Alt and a microphone for dictation. The docs list every toolbar key.
The terminal lives in the workspace, so a run carries on when you lock the phone. Open the app again and the output is waiting.
Questions
Can the Codex CLI run on a phone?
Not on the phone itself. The Codex CLI needs a Linux or macOS shell. Cosyra gives your phone a cloud Linux workspace where the CLI is already installed, and you drive it from the app's terminal.
Why use the device code sign-in on mobile?
Sign in with ChatGPT expects the browser to be on the same machine as the CLI. On a phone the CLI is in the cloud and the browser is in your hand, so the device code is the sign-in that fits: you open a link on any device and type a short code.
Do I need to install the Codex CLI first?
No. It is in the workspace already. Run codex --version to see which release you have.
Can I run Codex CLI without the interactive screen?
Yes. codex exec "your prompt" runs one task, prints the result and exits. It is useful on a mobile device because there is no menu to steer.
Does the same setup work on iPhone and Android?
Yes. The CLI runs in the cloud workspace, so the commands and your sign-in are the same from either app.
What does it cost?
Cosyra is a subscription: Core is $20 a month and Pro is $30 a month. Eligible new users can start a 7-day free trial in the App Store app. Codex usage is separate: it comes from your ChatGPT plan or is billed to your OpenAI API key.
Related guides
- Codex on your phone, the one-tap route with the ChatGPT sign-in sheet.
- Codex CLI on iPhone, Codex CLI on Android and Codex CLI on iPad.
- Claude Code on your phone and Cursor CLI on your phone.
- Claude Code vs Codex CLI on a phone, if you are choosing between them.