PyApp is a Rust-based CLI tool that builds standalone executables for Python applications. At build time, it embeds a Python distribution (CPython or PyPy) and the target Python project (as a wheel, source distribution, or dependency file) into a single binary. At runtime, the binary bootstraps itself by extracting the Python distribution, creating a virtual environment (or using full isolation), installing the project (optionally via pip or uv), and executing the specified Python code (module, script, notebook, or arbitrary code). It exposes optional management commands for cache management, metadata display, pip invocation, Python shell, self-update, and removal. The architecture is a monolith with clear module separation: build script (build.rs), runtime initialization (app.rs), distribution handling, compression, process management, and network download. The codebase is well-structured, uses modern Rust patterns (edition 2021, anyhow for error handling, clap for CLI), and includes comprehensive CI/CD pipelines. It is not a data research project; it is a packaging and deployment tool for Python applications.