How to compress PDF online free
To compress PDF online free, this page rebuilds the first selected PDF with object streams turned on, then downloads dangnh-compress.pdf. The original file stays where it was. There is no quality slider, no target size, and no page list, so every page of that first PDF is copied into the download.
A PDF saved without object streams can come out smaller, because this tool saves with object streams on. Pictures inside the file are copied as they already are. The page does not reduce the resolution of a scan, does not convert pages to grayscale, and does not promise a percentage. Compare the download with the original when you need to know whether it shrank.
1. Choose the PDF you want to slim down
Click Choose files or drop the document onto Choose PDF files. Several files can sit in the list, and compress rewrites only the first one.
2. Leave every page in the file
This tool has no Pages or ranges box, so you cannot ask it to compress page 1 alone. The download contains the full page list of the first PDF.
3. Click Compress PDF and save the download
The button stays disabled until a file is selected. The browser then downloads dangnh-compress.pdf. The page does not print a before-and-after percentage.
4. Compare the two file sizes yourself
A smaller download is possible when the rewrite packs the structure. An already compact file can stay about the same size, and a rewrite can also come out larger. The tool still saves dangnh-compress.pdf when the new file did not shrink.
Examples
These are honest outcomes of a structural rewrite. None of them is a guaranteed percentage.
A PDF that was saved loosely
A PDF saved without object streams can come out smaller, because this tool saves with object streams on. The page still does not claim a figure such as 40 percent.
A scan or a file full of images
A scan made of page images often shrinks little. The images are copied unchanged, and compress does not lower their quality or change their resolution.
A file that is already compact
A one-page PDF that is already tightly saved can stay about the same size, and it can also grow. Compress PDF still downloads dangnh-compress.pdf. It does not cancel the download when the new file is not smaller.
Limitations
No percentage is promised
Compression here is the object-stream rewrite described above. It is not image compression. Scanned and image-heavy PDFs may shrink little, and the page never promises a percent saved.
Compress does not remove a password
There is no password field on this compress page, so an encrypted PDF shows an error and is not changed.
The rewrite depends on device memory
The PDF is processed in browser memory on your device. A file larger than 50 MiB shows Large file: processing may use significant browser memory. There is no quality preset and no grayscale switch, and only the first selected PDF is compressed.