Free Online PDF Compressor
Large PDF files can be slow to email, upload, or share. LovePDFImg's PDF Compressor re-renders each page as a compressed image and assembles a new, smaller PDF. This works especially well for scanned PDFs, photo-heavy documents, and any PDF where reducing image quality is an acceptable trade-off for a much smaller file. Use the quality slider to balance size and readability, or switch to target size mode to aim for a specific KB or MB output.
All processing happens directly in your browser using PDF.js to read the document and pdf-lib to rebuild it - your file is never uploaded to a server, which keeps sensitive documents like signed contracts, medical records, or financial statements private throughout the entire process.
This tool is especially useful when a file needs to fit under an email attachment limit, a job application portal's upload cap, or a government form submission size restriction. Rather than guessing at settings, target size mode lets you specify exactly how small the output should be, and the tool works backward from there.
How the Compress PDF Tool Works
The tool uses PDF.js to render each page of your document as an image at your chosen resolution, then re-encodes that image as a compressed JPEG at the quality level you set. Those compressed page images are assembled into a brand-new PDF using pdf-lib. This rendering-and-rebuilding approach is why it works so well on scanned documents and photo-heavy PDFs - it directly targets the image data that's taking up most of the space, rather than trying to compress already-efficient text and vector content.
Who Uses Compress PDF?
Students: Shrink scanned assignments or textbook photocopies to fit under a school portal's upload limit.
Businesses: Reduce the size of scanned invoices, contracts, or reports before emailing them to clients or partners.
Professionals: Legal and admin teams compress large case files or scanned exhibits for easier storage and transfer.
Personal users: Shrink scanned ID documents, tax paperwork, or medical records before uploading them to an online form.
Why Choose LovePDFImg to Compress PDFs?
Compression tools from iLovePDF, Smallpdf, and PDF24 all handle this well, typically by uploading your file to a server for processing. LovePDFImg compresses your PDF entirely in your browser using PDF.js and pdf-lib, so your document never leaves your device. The tool includes a target size mode most competitors don't offer as prominently, requires no account, has no daily usage cap, and adds no watermark to the output.
Technical Explanation: PDF Compression
Most of a PDF's file size typically comes from embedded images rather than text, especially in scanned documents where every page is essentially a photograph. This tool addresses that directly by re-rendering each page at a controlled resolution and re-encoding it as a JPEG, which uses lossy compression to discard visual detail the eye is less sensitive to. The trade-off is that any selectable text in the original PDF becomes part of a flattened image after compression - which is why this method suits scanned or photo-heavy PDFs better than text-heavy documents where preserving selectable text matters.
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