General FAQ

What does Happy Coder do?

Happy Coder is a mobile app that lets you control coding agents on many different computers from your phone.

Is Happy Coder free?

Yes, completely free. Forever. No catches.

No subscription fees - Not now, not ever
No usage limits - Run as many sessions as you want
No user limits - Install on all your devices
Open source (MIT) - Fork it, modify it, sell it if you want

We’re not VC-funded. We’re not trying to get acquired. We just built a tool we wanted to exist.

Am I locked in?

No lock-in whatsoever. Here’s why:

Open source - The entire codebase is on GitHub
Self-hostable - Run your own relay server
Standard protocols - Uses WebSockets and AES encryption
No account required - No data to export or migrate
Works with vanilla Claude Code - Not a proprietary wrapper

You can stop using Happy Coder instantly with zero consequences. Your Claude Code setup remains unchanged.

What justifies your claim that Happy Coder is simple?

Happy Coder removes all the friction from mobile Claude Code access:

No signup process - Just download and run. No email verification, no account creation, no credit card. This is a real developer tool, not a SaaS product.
Cross-platform by default - Works on any computer (Mac, Windows, Linux) with any phone (iOS, Android). Control Claude Code on a Mac Mini from your Android phone. Run it on a Raspberry Pi and control it from your iPad.
It just works - Handles network issues gracefully. Reconnects automatically. Queues messages when offline. No broken SSH sessions or tmux corruption.
Smart error handling - Detects common problems and tells you exactly how to fix them. Port already in use? It tells you which process. Claude Code not found? It shows you where to install it.
Unix philosophy - Does one thing well: extends Claude Code to mobile. Doesn’t try to be an IDE, a project manager, or a cloud platform.

We built Happy Coder after suffering through overly complicated platforms that promise everything but fail at basics. Simple tools that work beat complex tools that don’t.

Why is Happy Coder free and Open Source?

Three reasons:

Privacy: Your code is your business. With end-to-end encryption and open source code, you can verify that we can’t see your work. No analytics, no tracking, no data mining.

Control: You own your tools. Run your own relay server. Modify the code. Add features. Remove features. It’s yours to shape as you need.

Sustainability: Open source projects can’t rugpull you. When a VC-funded startup pivots or shuts down, you’re stuck. Happy Coder will work as long as you want it to.

Does Claude Code have an app?

Yes! Claude Code has a mobile app called Happy Coder that lets you control Claude Code from your phone. Here’s how it works:

Download the Happy Coder app from the App Store (iOS) or Google Play (Android)
Install the companion software on your computer: npm install -g happy-coder
Run happy on your computer to start the connection
Scan the QR code with your phone to connect

Your phone and computer sync in real-time with end-to-end encryption, so you can start coding on one device and continue on the other seamlessly.

How do I install the Claude app?

For Happy Coder (mobile Claude Code client):

Download the Happy Coder app from your phone’s app store
On your computer, install: npm install -g happy-coder
Run happy command on your computer
Scan the QR code with your phone to connect securely

For Claude Code (desktop CLI):

Install with npm: npm install -g claude-code
Set up your API key
Works on Mac, Windows, and Linux

For regular Claude (AI chat): Just visit claude.ai in your web browser.

Platform Availability

Can you use Claude on mobile?

There are two different products to understand:

Claude (AI chat): Yes, go to claude.ai on any mobile browser.

Claude Code (developer tool): Yes, through the Happy Coder mobile app! This lets you control Claude Code running on your computer from your phone. You can:

Start coding conversations on your phone
Continue the same conversation on your computer
Switch back and forth without losing context

Does Claude have an Apple app?

Claude (AI chat): Anthropic has an official iOS app, or you can use claude.ai in your browser.

Claude Code: Yes! The Happy Coder app is available on the App Store for iPhone and iPad. It’s free, 100% open source, and the best way to use Claude Code on mobile.

Can I do coding in a mobile app?

Absolutely! The Happy Coder app is designed for mobile coding, but it’s smart about what works well on mobile vs. desktop:

Great mobile tasks:

Planning new features during your commute
Brainstorming solutions while away from your desk
Voice conversations with Claude Code for rubber duck debugging
Setting up coding tasks before bed (Claude Code works while you sleep!)
Getting push notifications when code changes are ready

Great desktop tasks:

Reviewing generated code with multiple windows
Making precise edits with your full IDE
Testing and debugging with all your tools

The magic is seamlessly switching between both in the same conversation.

Usage and Features

How to use the Claude app?

For Happy Coder mobile app:

Download and install the app
Set up the desktop connection (see installation above)
Scan the QR code to connect
Start chatting with Claude Code from anywhere!
Use voice features for hands-free coding discussions

For regular Claude: Visit claude.ai and start chatting.

For desktop Claude Code: Use terminal commands like claude-code "help me fix this bug"

Which Claude is best for coding?

Claude-4.1 Opus is currently the best model for coding. It offers:

Great understanding of your code
Smart problem-solving
Ability to work with large projects
Fast and accurate responses

Claude-4 Sonnet is also a great model for coding.

Claude Code and Happy Coder automatically use the best model for your tasks.

GPT-5 is slower.

Pricing and Plans

How much does Claude code cost?

Claude Code uses a subscription with pay-as-you-go pricing for overages:

Typical cost: $20, $100, $200 per month plans.
No free tier: Claude Code does not offer free usage when you start
Apps are free: The Happy Coder app and Claude Code CLI cost nothing
Enterprise options: Special plans for teams

The exact cost depends on:

How complex your coding tasks are
How long your conversations are
Which AI model you’re using

App Features

The Happy Coder mobile app includes:

Open source: MIT License (check out the code at github.com/slopus/happy )
Native mobile design: Built specifically for phones and tablets
Seamless workflow: Perfect sync with your computer
End-to-end encryption: Your code stays private
Voice interaction: Talk to Claude Code hands-free
Push notifications: Know when your code is ready
Offline-friendly: Queue up tasks even with poor connection

Comparison with Alternatives

Is Claude better than ChatGPT for coding?

Both are good, but Claude Code offers unique advantages:

Better project understanding: Knows your entire codebase
Mobile coding: Work from anywhere with Happy Coder
Direct file editing: Makes changes to your actual code files
IDE integration: Works with VS Code, Cursor, and other editors
Large project handling: Better with complex, multi-file projects

ChatGPT is also excellent for explaining code and generating examples.

The best choice depends on your workflow and what you need.

Technical Questions

What’s the latency between phone and desktop?

Typically around 300ms. This includes:

Encryption/decryption time (~10ms)
Network round trip (~200ms on average)
Processing overhead (~90ms)

For comparison, SSH over mobile usually has 100-200ms latency but with terrible mobile UX.

Can I use Happy Coder with multiple Claude Code sessions?

Yes! You can run multiple sessions simultaneously:

Different sessions on different machines
Multiple sessions on the same machine (different ports)
Switch between sessions instantly on your phone
Each session maintains its own context and history

Does Happy Coder work with MCP tools?

Full support for all MCP (Model Context Protocol) tools:

Your existing MCP configurations work unchanged
All MCP tools available on desktop work through mobile
Permission prompts appear on your phone for approval
Custom MCP tools are fully supported

Can I use custom Claude Code agents?

Yes, all your custom agents work perfectly:

Agents in ~/.claude/agents/ sync automatically
Custom slash commands work from mobile
Agent switching preserves conversation context
Create new agents from your phone

What happens if my connection drops?

Happy Coder handles disconnections gracefully:

Messages queue on your device until connection returns
Claude Code keeps working on your computer
Automatic reconnection when network returns
No lost messages or broken sessions
Pick up exactly where you left off

Can I review code changes before Claude Code applies them?

Yes, Happy Coder shows you:

File diffs for all changes
Permission prompts for file operations
Ability to rollback to checkpoints
Full visibility into what Claude Code is doing

Security & Privacy Questions

Can Happy Coder or the relay server see my code?

No. Everything is end-to-end encrypted:

Encryption happens on your device before sending
Relay server only sees encrypted blobs
Only devices with the shared key can decrypt
We literally cannot read your code even if we wanted to

Is my company’s proprietary code safe?

Yes, Happy Coder is designed for enterprise use:

End-to-end encryption protects your IP
Self-host the relay server on your infrastructure
No data ever touches our servers if self-hosted
Open source code you can audit
No analytics or telemetry

What data does Happy Coder collect?

None. Zero. Nothing.

No user accounts or emails
No usage analytics
No error reporting
No telemetry
No cookies or tracking

The only data that exists is encrypted blobs on the relay server, which we can’t read.

Troubleshooting

”Claude Code not found” error

Happy Coder needs Claude Code installed first:


npm install -g claude-code
claude-code --version  # Verify installation
happy  # Now this should work

QR code won’t scan

Common fixes:

Increase screen brightness
Clean your camera lens
Make QR code bigger: happy --qr-size large
Use manual code: happy --no-qr (shows text code to type)

“Port already in use” error

Another process is using port 8765:


# Find what's using the port
lsof -i :8765
 
# Kill it
kill -9 [PID]
 
# Or use a different port
happy --port 8766

Can’t connect to relay server

Check if you’re behind a corporate firewall:

Try using cellular data instead of WiFi
Ask IT to whitelist relay.happy.engineering
Or self-host your relay server

Need More Help?

For more information about Claude Code and Happy Coder:

Read our Quick Start Guide
Learn How It Works
Check the CLI Reference
Visit GitHub Issues

Have specific questions? The developer community is here to help!