macOS GPT-LLM Playground: macOS GPT-LLM Playground is a native Mac IDE designed specifically for Prompt Engineering with Time Travel. It offers Versioning, Full-Text Search, Multi-Model support, Combinatorial Runs, Variants, Model-Cost Aware features, API integration, Token Stats, Custom Endpoints, Local Models, Tables, Syntax highlighting, LaTeX support, Notes Export, Shortcuts, Vim Mode, and a Sandbox environment. It is built with Cocoa, SwiftUI, and SQLite.