Local PDF Tools is a free, open-source web app that lets you compress, merge, and split PDF files directly in your browser—no uploads required. Powered by Ghostscript WebAssembly, all processing happens locally for maximum privacy. Features include quality presets, custom Ghostscript commands, real-time terminal output, and progress tracking. Licensed under AGPL v3.
Try it at: https://krmanik.github.io/local-pdf-tools/
GitHub: https://github.com/krmanik/local-pdf-tools