What it does

Happy is a harness for coding agents. You use it to run Claude, Codex and Grok from one app, and each model keeps the prompts and tools its own vendor ships. You can pick the model that suits each task and hand work to subagents on any of them. It signs in with the Claude, Codex and Grok subscriptions you already pay for, so it adds no extra bill of its own. The code is MIT licensed, runs on your own hardware, and your projects stay as ordinary folders. Sessions follow you to your phone. The mobile app shows the same sessions as your desktop, and the site says what moves between your devices is encrypted. A team server can also be deployed so people sign in as themselves and share projects and sessions. If you prefer the terminal, a command-line tool installs with npm. You start Claude Code or Codex through it, then resume that session or start a new one from your phone without the desktop app.

Capabilities

Runs Claude, Codex and Grok agents side by side in one app
Signs in with your existing Claude, Codex and Grok subscriptions
Subagents can be delegated to on any of the supported models
Encrypted mobile app that shows the same sessions as your desktop
Team server so several people share projects and sessions
Terminal command-line tool for starting Claude Code or Codex sessions

When to use it

You use more than one coding agent and want a single place to run them
You want to check on or continue an agent session from your phone
You want an open-source tool that works with subscriptions you already have
Your team wants to share agent projects and sessions on its own server