Modufile's Compress PDF tool reduces your PDF file size directly in your browser using the MuPDF rendering engine compiled to WebAssembly. It performs garbage collection, stream recompression, object deduplication, and removal of unused resources — optimizing the internal structure of the file without degrading visual quality. Since all processing happens client-side, your files are never uploaded to any server, making this a private and secure alternative to cloud-based PDF compressors like Smallpdf or Adobe's online tool. It works well for shrinking PDFs before email, upload, or archival.