PDF Compressor
Re-save a PDF with object streams in your browser. File-size reduction depends on the source PDF and is not guaranteed.
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PDF Compressor online
Reduce a PDF's file size by re-saving it with a modern, compact internal structure — no upload and no server involved. It works best on PDFs bloated by the software that produced them; already-optimised files may barely change.
How it works
The tool loads your PDF with a JavaScript PDF library and saves it again using object streams and a compressed cross-reference table — modern PDF structures that pack many small objects together instead of scattering them, uncompressed, through the file. This strips out the redundancy left by repeated edits and by producers that write loose structures. What it deliberately does not do is re-encode the content: embedded images keep their original resolution and compression, and text is untouched, so the document renders identically afterwards.
Worked example
A report exported from a word processor at 4.8 MB often carries uncompressed internal structures, and re-saving typically trims it noticeably. A 20 MB scanned document, by contrast, is almost entirely image data — re-saving its structure might save only a few percent, because the bulk of the file was never structural. The page reports the new size after processing, so you can judge the result file by file.
How to use this tool
- Choose the PDF file from your device.
- Run the compression — the file is re-saved locally with object streams.
- Save the result and compare sizes; if it did not shrink, keep your original.
Common uses
Fitting PDFs under email and portal upload limits, shrinking document archives, and preparing files for web publishing, where every extra megabyte slows readers down.
Privacy and browser processing
The PDF is processed entirely in your browser — it is never uploaded, so private documents stay on your device.
Frequently asked questions
Why didn't my PDF get smaller?
Because its bulk is image data, embedded fonts or content streams that were already compressed. This tool optimises the file's internal structure only, and a scanned document is nearly all image — there is little structure to save. That is also why no reduction is ever promised.
Will the document quality change?
No. Images are not downsampled and text is not altered, so every page renders exactly as before. A much smaller file at lower image quality would require re-encoding the images, which is a different kind of processing.
Is my PDF uploaded to a server?
No. The file is parsed and re-saved in your browser with JavaScript and never leaves your device, which makes the tool suitable for contracts and personal documents.
Can it compress a password-protected PDF?
No. An encrypted PDF cannot be parsed until its protection is removed. Unlock the file first, then compress the unlocked copy.