Reduce the size of a PDF without uploading it anywhere. The file is optimized and re-saved entirely in your browser, then downloaded back to you.
SYSTEM ● ONLINE · LOCAL COMPUTE · ZERO UPLOAD
UNIT // PDF.COMPRESSLIVE
Drop a PDF file
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Original
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Compressed
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Saved
Quick Answer
How do you compress a PDF?
// Answer
A PDF compressor reduces file size by rewriting the document with optimized object streams and stripping redundant data. This tool loads your PDF, re-saves it with object streams enabled directly in your browser, and hands back a smaller file. Because everything runs locally, your document is never uploaded to a server.
What compression does
This tool rewrites the PDF using compressed cross-reference and object streams, which removes structural overhead and can shrink some PDFs — most often ones built up across several rounds of edits, or written by software that does not compress the file's structure. The visible content and page layout stay intact.
Note that PDFs whose size is dominated by already-compressed JPEG photos will compress less, since the images themselves are not re-encoded.
Why use this tool
Private by design
Many online PDF compressors upload your document to their servers. This one does all the work in your browser using a local library, so confidential contracts, statements, and reports never leave your device.
FAQ
Frequently asked questions
Drop your PDF here; it is optimized and re-saved smaller in your browser, with nothing uploaded.
No. Compression happens entirely on your device, so the file stays private.
PDFs dominated by already-compressed photos have little structural overhead to remove. Files edited and re-saved many times have the most to lose.
Page content and layout are preserved. This method optimizes structure rather than re-encoding images, so text stays crisp.
This tool rewrites the structure of your PDF. It does not touch the pictures inside it. A document saved over and over, or written by software that does not compress its structure, can lose real weight that way. A scanned document is a photograph of a page, so it comes out close to the size it went in. If the Saved figure reads 0%, keep your original.
That is the whole trade. The rewrite is safe because nothing is thrown away, and it is limited for exactly the same reason.
Mechanism
What gets rewritten, and what is left alone
The file is parsed, then written out again as a single current revision with compressed object and cross-reference streams. Everything the pages point at is carried across untouched.
Part of your PDF
What happens to it
Cross-reference table and object streams
Rewritten and compressed. This is where the saving comes from
Superseded data from earlier saves
Not carried into the new revision
Photos and scanned pages
Untouched. Not re-encoded, not reduced in resolution
Embedded fonts
Untouched. Not subset, even if the document uses six letters of one
Annotations, comments, attachments
Carried over
Author, title, creation date
Left exactly as found
Fast web view (linearisation)
Not rebuilt, so a very large file may start displaying later online
Because metadata is deliberately left alone, this is not a redaction step. The author name and the software that made the file travel with it.
The case it cannot win
Scanned documents behave completely differently
Open a scan and look at one page. You cannot select the words, because there are none. Each page is a single large image, often already compressed by the scanner. There is almost no structure to squeeze, so a structural compressor has nothing to work with.
The size lives in the pixels, so that is where you have to go. The route that works, using tools on this site:
If the scan is still a set of image files, shrink them first with compress image, or cut their width with resize image. Width is the bigger lever of the two.
Run the result back through this page to tidy the structure.
If the scan only exists as a PDF, this tool cannot re-scan it for you. Reducing the scanner resolution and scanning again is usually faster than fighting the file.
Limits
When not to use this
The PDF is digitally signed. Any rewrite changes the bytes the signature covers, so the signature stops validating. Send the signed file as it is.
The PDF has a password. Encrypted files are not opened here. You get a short message saying the file could not be read. Remove the password in the application that set it, then come back.
You need PDF/A for an archive or a court filing. A rewritten file may no longer validate as PDF/A. Check before you rely on it.
You wanted metadata gone. It is preserved here on purpose. That is a different job, not a smaller file.
The file is damaged. Parsing is strict. A malformed PDF that a desktop reader quietly repairs on open may simply fail here. Open it in a reader and export a fresh copy first.
Worked example
An email bounced your 12 MB attachment
First, a detail that catches people out: mail attachments are base64-encoded in transit, which adds roughly a third to the size on the wire. A file sitting comfortably under the stated cap can still be refused.
Drop the PDF here and read the Saved figure. If it is a decent double-digit percentage, you are done.
If it is 0% or close, you have a scan or a photo-heavy file. Do not keep compressing it.
Ask what the recipient actually needs. Two signed pages out of forty is a split, not a compression problem, and it will get you past any limit.
If they need all of it, send a link from a storage service instead of an attachment.
For images rather than documents, start at the compression tools, which cover the formats where large savings are genuinely available.
Privacy
Why it matters that this one stays on your machine
Think about which PDFs you actually try to shrink. A signed contract. A payslip. A passport scan for a visa form. A letter from a hospital. A tax return. These are the documents that would cost you the most if they sat on a stranger's disk.
A conventional online compressor needs your file on its server to work on it. You are then trusting a retention policy you have not read, on infrastructure you cannot inspect. Here the library runs in the tab, the work happens on your processor, and the finished file is handed to your downloads folder. Nothing is stored, which also means there is no link to share and no copy to come back for. Reload the page and the result is gone.