Local PDF Compressor

The Secure PDF Compressor reduces the file size of PDF documents using browser-side processing. It is designed for users who regularly deal with large PDF files — scanned documents, image-heavy reports, brochures, and portfolios — and need to reduce their size for email attachment limits, upload portals with file size caps, or simply more efficient storage.

PDF file size is dominated by the images embedded within the document. A text-only PDF is typically small regardless of page count. A PDF containing scanned pages — each page an embedded JPEG or PNG image — can be tens of megabytes. Compressing the embedded images at a reduced quality level dramatically reduces the total file size.

The tool uses pdf-lib and the Canvas API to process the PDF in the browser. Pages are decoded, embedded images are identified and re-encoded at the chosen compression level, and a new PDF is assembled with the compressed images. Text content and vector graphics are not affected by compression and remain sharp regardless of the quality setting.

Three compression levels are typically offered: light, standard, and aggressive. Light compression applies moderate image quality reduction and typically achieves 20 to 40 percent size reduction. Standard compression is suitable for most sharing purposes and achieves 40 to 60 percent reduction. Aggressive compression maximises size reduction but reduces embedded image quality noticeably — suitable for archiving purposes or situations where exact image fidelity is not required.

Because the process runs locally, files containing personal documents, financial records, legal contracts, or medical information are not transmitted anywhere. This is the key distinction from online PDF compression services such as ILovePDF, Smallpdf, or Adobe's online tools, which all require file upload.

Secure PDF Compressor is part of the Envizion Tools2 collection at envizion.work.