Compress PDF
Shrink a PDF with a lossless structural rewrite that drops redundant and orphaned objects. Actual before and after byte counts are always shown.
Runs in your browser — nothing is uploadedFree trial: 1 run of Compress PDF every day. After that, 2 credits per run.
Rewrite a PDF so repeated editing stops costing you megabytes
A PDF that has been edited and re-saved repeatedly collects orphaned objects and duplicated resources. This rebuilds that structure, which on such files can cut the size without touching a pixel. It does not downsample or re-encode images, so a PDF dominated by a scan will barely change — and no percentage is promised, because none can be promised before seeing the file.
What Compress PDF gives you
Structural rewrite
The document is rebuilt with its internal objects packed into streams, removing redundancy left by repeated saving.
Before and after, in bytes
You see the original size, the new size and the percentage saved — not a vague "optimised" label.
Tells you when it did not help
If the rewrite makes no saving you are told plainly and pointed back to your original.
Page content left alone
Text, images and layout are untouched, so the document looks exactly as it did before.
Runs on your device
A confidential document is never uploaded to be made smaller.
How to use Compress PDF
Add the PDF
Files up to 150 MB and 500 pages are accepted.
Run the rewrite
The document is parsed and rebuilt in memory on your device.
Compare the sizes
If the saving is worthwhile, download it; if not, keep the original you already have.
Other names for this tool
People also look for this as reduce PDF size, shrink PDF, make PDF smaller, optimise PDF and compress PDF online. It is the same tool on this page.
Looking for the opposite job? Images to PDF.
Limitations
- A structural rewrite is lossless and may not reduce size at all.
- Image data is never re-encoded, so scans are largely unaffected.
Questions about Compress PDF
How much smaller will my file be?
It depends entirely on the source. A structural rewrite often helps repeatedly-edited documents and may do nothing for a scan. No percentage is promised.
Why did my file not get smaller?
A scanned PDF is mostly image data. A lossless rewrite only removes redundancy in the file structure, so it cannot shrink the images themselves.
How do I reduce PDF file size without losing quality?
A structural rewrite is the only lossless route, and it is what this tool does. Nothing is re-rendered or recompressed, so the document looks identical afterwards. The saving comes from discarding internal clutter, not from degrading the content.
Why did my scanned PDF barely get smaller?
Because its size is in the images, and images are deliberately left alone. A rewrite cannot help there. Re-export the pages at a lower resolution from your scanner or PDF editor, which does lose quality but is the only thing that shifts a scan-heavy file.
What kind of PDF benefits most?
One that has been through many rounds of editing and re-saving. Those accumulate orphaned objects and duplicated resources, and rebuilding the structure clears them out for no loss of quality at all.
What if the result is bigger than the original?
That happens when a document was already tightly optimised, and you are told plainly and pointed back to your original. The tool will not hand you a larger file and call it a success.
Should I compress before or after merging?
After. Merging rebuilds the document anyway, so a rewrite done first is simply undone. If size is the real goal, deleting pages you do not need saves far more than any rewrite can.
How large a file can it handle?
Up to 150 MB and 500 pages. The page ceiling is lower than the other PDF tools because rebuilding every object in a very long document is the heaviest operation here and a browser tab has a finite memory budget.