# PDF.js > This is a modified version of the pdf.js v3.10.111 legacy prebuild. [PDF.js](https://github.com/mozilla/pdf.js/) is a Portable Document Format (PDF) viewer that is built with HTML5. PDF.js is community-driven and supported by Mozilla. Main goal is to create a general-purpose, web standards-based platform for parsing and rendering PDFs. ## Changes Changes made to the pdf.js v3.10.111 legacy prebuild can be seen from https://gitea.rkg.lv/yellowmonarch/pdf.js/commit/2dca5acb42913874baaad4d377a3be675978ba13 ## Compression Minified, using (installed via `npm`): ```sh css-minify --file viewer.css -o out uglifyjs pdf.js -o pdf.js --source-map ```