If you use more than one coding agent, you know the juggling: Claude Code in one terminal, Codex in another, Cursor in its own window. T3 Code puts them behind one interface, and lets you check on them from your phone. It drew about 2,000 posts in our X sample this week.
What it is
T3 Code describes itself as an "agent harness control surface". It doesn't ship a model or an agent of its own. It controls the agents already installed on your computer, using your existing subscriptions:
- Claude Code
- Codex
- Cursor
- Grok Build
- OpenCode
- Google Antigravity
You get it as an Electron desktop app, a web app, and iOS and Android apps. Agents keep running on your machine; the phone app is a remote control.
The project is open source under MIT. As of Oct 22, its GitHub repo had about 29,400 stars.
Not sure what a "harness" is? Our explainer on agent harnesses and Google's Harness² covers it.
Step 1: set up at least one agent
T3 Code needs at least one provider installed and logged in. From the README:
| Agent | Log in with |
|---|---|
| Codex | codex login |
| Claude Code | claude auth login |
| Cursor CLI | agent login |
| Grok Build | grok login |
| OpenCode | opencode auth login |
| Antigravity | In T3 Code Settings: Install Antigravity, then Sign in with Google (no CLI needed) |
New to Codex? Start with our Codex CLI getting-started guide.
Step 2: install T3 Code
Command line (Mac/Linux):
curl -fsSL https://t3.codes/install.sh | sh
Windows (PowerShell):
irm https://t3.codes/install.ps1 | iex
Then:
t3 # start the server and open the local web app
t3 service install # keep it running in the background
t3 update # update to a newer release
t3 --help # full reference
To try it once without installing anything: npx t3@latest.
Desktop app via package managers:
| Platform | Command |
|---|---|
| macOS (Homebrew) | brew install --cask t3-code |
| Windows (winget) | winget install T3Tools.T3Code |
| Windows (scoop) | scoop install extras/t3code |
| Debian/Ubuntu | download the .deb from GitHub Releases, then sudo apt install ./T3-Code-*.deb |
| Arch (AUR) | yay -S t3code-bin |
Step 3: connect your phone (optional)
Install the iOS or Android app and follow the repo's remote access guide in docs/user/. Take it seriously: remote control of a machine that runs shell commands is powerful, so set it up only on accounts and devices you trust.
What to check before relying on it
- It's early. In the README's words: "We are very very early in this project. Expect bugs."
- Permissions still matter. T3 Code has its own permission modes (documented in the repo), and your agents keep theirs. Keep both strict while you learn. See running coding agents safely.
- Your usage limits don't change. Every agent you drive through T3 Code still bills to its own subscription.
- Contributions are mostly closed. Small fixes may be considered; big features won't be.
Who it's for
- You use two or more agents and want one place to manage them.
- You want to start or check a task from your phone while away from your desk.
- You care about open source and the option to fork.
If you're still picking a single agent, start with our Cursor vs Claude Code vs Codex comparison. And if you want an agent running on a local model, see the OpenCode + Ollama guide.
