Parallel Code Review: Run AI Coding Agents Side by Side

Parallel Code is an open-source desktop app that runs Claude Code, Codex CLI, and Gemini CLI side by side. Each agent operates in its own isolated git worktree, and you review and merge from one interface. It's free, keyboard-first, and built to turn AI coding into a parallel pipeline.

What Is Parallel Code?

Parallel Code is an Electron-based desktop app that orchestrates multiple AI coding CLIs inside isolated git worktrees. Currently supported: Claude Code, Codex CLI, Gemini CLI, and Copilot CLI. Each task gets its own branch and working directory. You can dispatch multiple agents at once, monitor progress, review changes inline, and merge what you like. The state persists across restarts, and you can watch agents from your phone via QR code.

Built with TypeScript and SolidJS, it includes 10 themes, per-file test-coverage badges, a steps timeline, and an AI Arena mode to compare agent outputs head-to-head.

How Parallel Code Works

When you create a task, Parallel Code:

1. Creates a new branch from your current main branch.
2. Sets up a git worktree in a separate directory.
3. Symlinks node_modules and other gitignored directories to save disk space.
4. Spawns the AI agent CLI inside that worktree.

You monitor progress in a built-in terminal, see changed files, and review the diff with inline comments. When satisfied, merge the branch back to main from the sidebar. Everything is keyboard-controllable, and you can also use "Direct mode" without isolation for quick experiments.

Quick Start

1. Download the latest release from the releases page (macOS or Linux).
2. Install at least one AI coding CLI (links above).
3. Open the app, point it at a git repository, and start dispatching tasks.

Building from source:

git clone https://github.com/johannesjo/parallel-code.git
cd parallel-code
npm install
npm run dev

Requires Node.js 18+.

Real-World Parallel Code Workflow

Suppose you're working on a web app and need to:

• Refactor the authentication module
• Add error handling to API calls
• Write unit tests for the checkout flow

Instead of running these tasks sequentially, create three tasks in Parallel Code:

1. Task A: "Refactor auth to use JWT" -> agent works on branch refactor-auth
2. Task B: "Add error handling to API calls" -> agent works on branch error-handling
3. Task C: "Write tests for checkout flow" -> agent works on branch checkout-tests

Each agent runs in its own worktree. Switch between terminals, see diffs update in real time, and add review comments. When a task finishes, review the diff. If good, merge the branch. If not, discard and rerun with a refined prompt.

All three agents can finish in the time it normally takes to run one. No merge conflicts because each branch is independent until you decide to merge.

Parallel Code Pros and Cons

Pros

• True parallel execution of multiple AI coding agents
• Automatic git isolation via worktrees, no manual branch management
• Free and open source (MIT), no extra subscription
• Keyboard-first interface with extensive shortcuts
• Built-in diff viewer with inline code comments
• Monitor progress from your phone over Wi-Fi or Tailscale

Cons

• macOS and Linux only, no Windows support yet
• Requires at least one of the supported AI CLIs installed separately
• Git worktree overhead (each worktree duplicates non-symlinked files)
• Relatively young project (600+ stars, still evolving)

Alternatives and Verdict

• Multiple terminal windows / tmux: No GUI, no automatic git isolation. You manage branches and merges manually.
• VS Code extensions (Kilo Code, Roo Code, etc.): Tied to VS Code; no true parallel worktree isolation between agents.
• Running agents sequentially: One task at a time, blocks your workflow while each agent finishes.

If you already use Claude Code, Codex, Gemini CLI, or Copilot CLI and often run multiple tasks, Parallel Code is a no-brainer. It eliminates Git overhead and context switching. Free, open source, and well-designed. For Windows or single-agent workflows, skip it. But for power users on macOS or Linux, this tool multiplies your AI coding throughput.