Harmonic

What Harmonic is

Harmonic is a native Mac IDE for building with multiple AI agents. Each tab can run Claude Code, Codex, or DeepSeek, allowing separate agent sessions to run alongside each other. Each tab has its own Git worktree on disk. Users can queue completed tabs to merge into a base branch, review conflicts inline, and open pull requests in one pass. Harmonic supports connecting multiple GitHub accounts and assigning an account to each repository. Users can select an agent and model per tab; switching agents mid-conversation is available on Pro. A keyboard command palette supports actions such as changing tabs and opening repositories. The app requires macOS 11 or later and supports Apple Silicon and Intel Macs. Its Free plan costs nothing and can be used indefinitely without a card or account. Paid plans include $9 a month, $49 a year, and a one-time $79.00 USD Lifetime option. Harmonic's license covers the app, not agent access or AI usage; users bring their own plans and API keys.

Who it suits

Harmonic may suit Mac developers who want to run multiple coding-agent sessions in separate worktrees and coordinate merges. It requires users to provide their own agent plans and API keys.

Limits

The Free plan is limited to 2 repos, 5 tabs and one agent per chat. Agent access and AI usage are not included with the app; users use their own plans and API keys.

Getting started

1. Visit https://harmonic.build/.
2. Use the Free plan without a card or account, or choose a paid plan.
3. Install the app on a Mac running macOS 11 or later.
4. Bring your own agent plans and API keys.

Verdict

Harmonic focuses on organizing parallel coding-agent work and moving completed tabs toward a merge. Its app license does not cover access to the agents, so users need their own plans and keys.