Frequently Asked Questions

General

What is Arc0?

Arc0 is a mobile command center for coding agents like Claude Code, Codex, and Gemini CLI. It connects your terminal-based AI agents to your phone, so you can give direction, approve plans, monitor progress, and review changes—even when you're away from your desk.

Why do I need Arc0?

Coding agents need direction from you—you give them prompts, approve their plans, monitor progress, track changes, and review code. If you're away from your laptop (meetings, coffee, commute), your workflow stalls. Arc0 lets you direct from your phone, keeping work moving.

Is Arc0 free?

Yes. Arc0 CLI is open source (MIT license) and free to use. The mobile apps are also free.

Is my code safe?

Yes. Arc0 CLI runs locally on your machine. Your full codebase never leaves your computer. Only agent conversations and diffs are streamed to your phone over an encrypted WebSocket connection.

See Security & Privacy for details.

Compatibility

Which coding agents does Arc0 support?

Arc0 works with any terminal-based coding agent, with native support for:

• Claude Code (Anthropic)
• Codex CLI (OpenAI)
• Gemini CLI (Google)

Other agents work via tmux session detection.

What operating systems are supported?

Arc0 CLI (desktop):

• macOS (Intel and Apple Silicon)
• Linux (x64 and ARM64)
• Windows (x64)
• WSL

Mobile app:

• iOS 15.0+
• Android 10+

Does Arc0 work offline?

Partially. If you lose connection to Arc0 CLI:

• You can view cached sessions
• Pending responses queue locally
• Everything syncs when reconnected

But real-time notifications require an active connection.

Setup

How do I install Arc0?

1. Install CLI: brew install arc0 or npm install -g @arc0/cli
2. Download the mobile app (or use the webapp)
3. Run arc0 pair and scan the QR code
4. Run your agent in a tmux session

See Quickstart for full instructions.

Do I need to wrap every agent session?

No. Arc0 CLI automatically attaches to tmux sessions where your agents run. Just start your agent inside tmux:

tmux new -s dev
claude

Can I connect multiple phones to one CLI?

Yes. Run arc0 pair again to pair additional devices. All paired devices receive notifications.

Can I connect one phone to multiple CLI instances?

Yes. The app supports multiple CLI connections. Switch between them in the Sessions tab.

Usage

How do I respond to agent questions?

When you receive a notification:

1. Tap the notification (or open the app)
2. Read the question with context
3. Type your response or use quick replies
4. Tap Send

Your response is delivered to the agent instantly over WebSocket.

Can I review code diffs on my phone?

Yes. Arc0 includes a mobile-optimized diff viewer with:

• Syntax highlighting
• Unified or split view
• Approve/reject actions
• Inline comments

What if I miss a notification?

The agent waits for your response. Open the app to see pending questions. There's no timeout—respond when you can.

Can I use Arc0 without the mobile app?

The mobile app is the primary interface, but you can also use the webapp at app.arc0.ai.

Technical

How does Arc0 capture agent output?

Arc0 CLI attaches to your tmux sessions, capturing the terminal output of your coding agents. The agent runs normally—it doesn't know Arc0 is there.

Does Arc0 modify my agent's behavior?

No. Arc0 only observes and relays. Your agent runs exactly as it would without Arc0.

What data does Arc0 send to your servers?

By default, none. Arc0 operates entirely between your machine and your phone via a secure WebSocket tunnel. Optional telemetry (disabled by default) sends anonymized usage statistics.

Can I self-host everything?

Yes. Arc0 CLI is fully open source. You can:

• Run the CLI on your own server
• Build the mobile app from source
• Operate completely independently

What ports does Arc0 use?

• 3847 — Default local server port (configurable)
• 9090 — Prometheus metrics (optional)

Does Arc0 work behind a corporate firewall?

Yes. Arc0 uses a WebSocket tunnel that works behind NAT, firewalls, and corporate networks. No port forwarding required.

Troubleshooting

The app shows "Disconnected"

Check that:

1. Arc0 CLI is running (arc0 status)
2. Your internet connection is active
3. Firewall isn't blocking the connection

I'm not getting notifications

Check that:

1. Notifications are enabled in app settings AND device settings
2. Battery optimization is disabled (Android)
3. Focus mode isn't blocking Arc0 (iOS)
4. CLI has notifications.enabled: true

Agent questions aren't detected

Arc0 uses patterns to detect questions. For unsupported agents or formats, add custom patterns in config. See Troubleshooting.

Contributing

How can I contribute to Arc0?

We welcome contributions:

• Code: Submit PRs on GitHub
• Issues: Report bugs or request features
• Docs: Improve documentation
• Community: Help others on Discord

Where do I report bugs?

Open an issue on GitHub with:

• Arc0 version
• OS and version
• Steps to reproduce
• Relevant logs

Is there a roadmap?

Yes, see our GitHub project board. Planned features include:

• Apple Watch support
• Team collaboration features
• More agent integrations
• IDE extensions

Still Have Questions?