Large PDF files often exceed strict email attachment thresholds (usually 10MB–25MB) or online application portal limits (often capped at 2MB). Understanding how client-side PDF compression works helps you choose the optimal settings for your documents without unexpected trade-offs.
Client-side browser compression works by rendering document pages to an HTML5 canvas at target DPI resolutions (such as 72 DPI for extreme compression, ~100 DPI for balanced compression, and ~120 DPI for high quality) and encoding the resulting visual frames using JPEG stream compression.
Because pages are rasterized into visual images during in-browser compression, graphic layout, logos, signatures, and visual appearance are preserved according to your chosen quality level, while vector characters are baked into the page image. For documents where text copyability is essential, splitting large PDFs or selecting higher quality profiles helps balance file size with clear readability.