Prompt Builder

A native macOS app for assembling large context prompts from your codebase. Select files from a project tree, add instructions, and copy the complete prompt to clipboard — ready to paste into Claude, ChatGPT, Ollama, or any other LLM.

Why?

Modern LLMs like Claude (up to 1M tokens) and GPT-4 (128k) can digest entire codebases in a single prompt. The challenge is assembling that prompt — selecting the right files, formatting them properly, and keeping track of the token count.

RepoPrompt does this, but it costs money and caps you at ~35k tokens. Prompt Builder is free, open-source, and has no token limit — build prompts as large as your model can handle.

Features

• Native macOS app — built with SwiftUI, single binary (~380KB), no Electron, no runtime dependencies
• Project file tree with recursive folder selection and tri-state checkboxes (checked / unchecked / partial)
• Smart file filtering — automatically skips node_modules, .git, binary files, and respects .gitignore
• Exclude patterns — filter out files by glob masks (e.g. *.css, *.md, *.test.ts)
• Live token counter — estimates token count as you select files
• One-click copy — builds the prompt and copies to clipboard in one action
• Structured output — generates <file_map>, <file_contents>, and <user_instructions> XML sections

Output Format

The generated prompt has three XML sections:

<file_map> — ASCII tree of the project with * marking selected files:

/path/to/project
├── src
│   ├── api
│   │   └── client.ts *
│   └── main.tsx *
└── package.json

<file_contents> — full source code of each selected file, wrapped in fenced code blocks with language detection.

<user_instructions> — your custom instructions/prompt.

Install

Homebrew

brew install --cask alexrett/tap/prompt-builder

Download

Grab the latest PromptBuilder.dmg from Releases.

Signed and notarized with Apple Developer ID — no Gatekeeper warnings.

Build from Source

Requires Xcode Command Line Tools and macOS 13+.

git clone https://github.com/alexrett/prompt-builder.git
cd prompt-builder
swift build -c release
open .build/release/PromptBuilder

To build a universal binary (Intel + Apple Silicon):

swift build -c release --arch arm64 --arch x86_64

Create .app Bundle

# Build
swift build -c release --arch arm64 --arch x86_64

# Create bundle
mkdir -p PromptBuilder.app/Contents/MacOS PromptBuilder.app/Contents/Resources
cp .build/apple/Products/Release/PromptBuilder PromptBuilder.app/Contents/MacOS/
cp AppIcon.icns PromptBuilder.app/Contents/Resources/

cat > PromptBuilder.app/Contents/Info.plist << 'EOF'
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>CFBundleExecutable</key>
    <string>PromptBuilder</string>
    <key>CFBundleIdentifier</key>
    <string>com.whitehappypony.prompt-builder</string>
    <key>CFBundleName</key>
    <string>Prompt Builder</string>
    <key>CFBundlePackageType</key>
    <string>APPL</string>
    <key>CFBundleShortVersionString</key>
    <string>1.0</string>
    <key>CFBundleIconFile</key>
    <string>AppIcon</string>
    <key>LSMinimumSystemVersion</key>
    <string>13.0</string>
    <key>NSHighResolutionCapable</key>
    <true/>
</dict>
</plist>
EOF

Usage

1. Open Folder (⌘O) — select your project directory
2. Select files — click folders to select recursively, click individual files to toggle
3. Exclude patterns — type glob masks like *.css, *.md, *.test.ts and press Apply
4. Add instructions — write your prompt in the Instructions panel
5. Copy Prompt (⌘⇧C) — builds and copies the complete prompt to clipboard

You can also pass a project path as a CLI argument:

./PromptBuilder /path/to/your/project

Keyboard Shortcuts

Shortcut	Action
⌘O	Open folder
⌘⇧C	Build & copy prompt

Requirements

• macOS 13.0 (Ventura) or later
• Works on both Apple Silicon and Intel Macs

License

MIT