Run Claude Code and Codex from one app with T3 Code

Running Claude Code in one terminal and Codex in another gets old quickly. Sessions scatter across windows, and you cannot check on a long run from your phone.

T3 Code is an open-source "agent harness control surface". It sits on top of the agent CLIs you already have, including Claude Code, Codex, Cursor, Grok Build, OpenCode and Antigravity, and gives you one local web app, a desktop app and mobile apps to drive them. It does not replace your subscriptions. If an agent is set up on your computer, T3 Code can control it.

Before you start

Install and sign in to at least one provider first. From the README:

codex login
claude auth login
agent login

Those are Codex, Claude Code and Cursor CLI respectively. You only need one.

Install

The quickest route is the one-line installer:

curl -fsSL https://t3.codes/install.sh | sh

That pipes a script from the internet into your shell, so read it first if that is your policy. Alternatives from the README:

npx t3@latest
brew install --cask t3-code
winget install T3Tools.T3Code

The npx line runs it once without installing. Homebrew covers macOS, winget covers Windows.

Run it

t3

That starts the server and opens the local web app. Two more commands from the README are worth knowing:

t3 service install
t3 update

t3 service install keeps it running in the background, and t3 update moves you to a newer release. t3 --help has the full reference.

What to try first

Open a project in the web app, pick Claude Code as the provider, and give it a small task such as "add a unit test for the date parser". Then start a second thread with Codex on a different task. Both run from the same window, so you can compare how each agent handles the work without juggling terminals.

A prompt you can paste

"Install T3 Code with npx t3@latest, confirm that claude auth login is already done, then open the local web app and tell me the URL. Do not run the curl installer."

Caveats

• The README says the project is very early and to expect bugs.
• Your agent CLIs still use your own subscriptions, so usage limits and costs come from those providers.
• This walkthrough follows the README and has not been run end to end by us. Check the repo for newer instructions.

More

Step-by-step card: Run Claude Code and Codex from one app instead of terminals. Compare more options on the Claude Code use case index.

Source repo: pingdotgg/t3code.

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