Compress PDF
Reduce PDF file size by rebuilding and optimizing the document.
Only the first file is used. Remove it to use a different one.
Use commas between pages and a dash for a range.
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This tool rewrites a PDF with a more compact internal structure to cut its file size without touching the text, images or layout. Drop in a file, press Compress PDF and download the result. It is lossless, so there is no quality setting to choose; how much it saves depends entirely on how the original was put together.
What the compression actually does
A PDF is a set of numbered objects (pages, fonts, images, text streams) plus a cross-reference table that says where each object sits in the file. Some PDF writers store the descriptions of all those small objects as plain, uncompressed text. This tool loads the document with the pdf-lib library and saves it again using object streams, a feature added in PDF 1.5 that bundles small objects together and compresses them, and stores the cross-reference table in compressed form too.
Page content, fonts and embedded images are copied exactly as they were. Nothing is resampled or converted to greyscale, which is why the output looks identical to the input.
What result to expect
- Files with an uncompressed structure, often produced by older software or simple report generators, can shrink noticeably.
- Files that are already compactly structured change very little, and occasionally come out the same size or a touch larger. In that case keep your original.
- Scanned documents and photo-heavy PDFs barely change, because almost all of their weight is in the images, and the images are left alone.
Getting a scanned PDF under an upload limit
Exam, job and government portals often cap uploads at a few hundred KB. When a scan is too big, the images need to shrink, and there are two routes:
- Rescan smarter. 150 to 200 DPI is plenty for a document that will be read on screen, and greyscale is smaller than colour. Resolution at scan time has the biggest effect of anything you can change.
- Rebuild from smaller images. Turn the pages into images with PDF to JPG, reduce them with the image compressor, then join them again with Image to PDF.
The rebuild route turns every page into a picture, so text can no longer be selected or searched. It suits scanned forms and certificates, not documents whose text people need to copy.
What this compressor does not do
- It has no quality slider and does not downsample or recompress images.
- It does not remove fonts, metadata or attachments.
- It does not add or remove passwords; unlock a protected file before processing it.
Because the work happens in your browser, confidential statements and ID documents stay on your device throughout.