Compress a PDF Without Uploading It
Make a PDF smaller by recompressing the images inside it, keeping the text sharp and selectable. Runs in your browser with no upload.
Runs entirely in your browser — nothing is uploaded
Where a PDF’s size actually comes from
Almost always, from pictures. A ten-page report of pure text is a few hundred kilobytes; ten pages photographed with a phone is thirty megabytes. The text is not the problem, and no amount of clever compression will make a text document meaningfully smaller — its size is embedded fonts and page structure, both of which are already compact.
This matters because it tells you what to expect. If your PDF is a scan, an exported presentation, or anything with photographs in it, the savings here are dramatic. If it is a contract typed in Word, it will barely move, and that is not a failure of the tool.
The two modes
Recompress images — the default
Finds the pictures stored inside the document, re-encodes them smaller, and puts them back. Everything else is left exactly as it was, so text stays selectable and searchable, fonts stay embedded and vector graphics stay sharp at any zoom.
This is what you want in nearly every case. A scanned contract shrinks by 70 to 90 percent and still behaves like a proper document.
Flatten pages — the heavy option
Redraws every page as one flat image and builds a new document from those. It compresses harder and works even on files the first mode cannot touch, but the document stops being a document: no selectable text, no search, nothing a screen reader can read.
Reach for it when a hard size limit leaves no choice, and when the file was already just pictures of pages. Never use it on something the recipient needs to work with.
The two settings
Image quality is the usual JPEG trade-off. 65 is a good default for scanned text, which tolerates aggressive compression because it is mostly white. Photographs want 75 or above.
Maximum image size caps how many pixels each picture keeps, and it is where most of the saving really comes from. A page photographed at twelve megapixels holds several times more detail than a printer can reproduce, let alone a screen. Capping the longest edge at 1600 pixels is invisible in practice and can shrink a file by more than quality ever will.
What is left alone, and why
Only images already stored as JPEG are replaced. Some PDFs store pictures in other encodings that a browser cannot decode without a dedicated decoder for each one, and guessing at them is how tools corrupt pages. Those images are reported as skipped and passed through untouched.
The tool also refuses to swap in an image that came out larger than the original, which happens routinely with already-optimised files. A compressor that quietly inflates your document is worse than one that does nothing.
Do not compress twice
Each pass permanently discards detail, and the second pass gains far less than the first while costing just as much quality. If the result is not small enough, go back to the original and lower the settings rather than compressing the compressed file.
Nothing is uploaded
The document is opened, rebuilt and handed back entirely inside your browser. That matters here more than for most tools: the PDFs people need to shrink are usually the ones they are about to send to a bank, a landlord, an employer or a government form — exactly the documents that should not be sitting on a stranger’s server.
Frequently asked questions
Why did my PDF barely get smaller?
Because there was little to remove. Compression here works on the images inside the document, so a PDF made of text and vector graphics is already close to as small as it can be — its size comes from embedded fonts and page structure, not from pictures. Scanned documents and photo-heavy files are where the large savings are.
What is the difference between the two modes?
Recompress images rebuilds only the pictures inside the file and leaves everything else alone, so text stays selectable and searchable. Flatten pages redraws every page as one image, which compresses much harder but turns the whole document into pictures. Use the first unless you genuinely need the smaller result.
Will flattening make my text unsearchable?
Yes, and that is the trade. After flattening you cannot select, search or copy any text, and a screen reader cannot read the document. It is the right choice for a scan that was already just pictures, and the wrong one for a contract or a report someone needs to work with.
How small can I expect the file to get?
A scanned document at full camera resolution often drops by 70 to 90 percent with no visible difference, because the original held far more detail than any screen or printer uses. A text document may not move at all. The tool shows the before and after so you can judge rather than guess.
Can I compress the same PDF twice?
You can, but each pass discards detail permanently and the second pass gains far less than the first. If the result is not small enough, go back to the original and use a lower quality setting rather than compressing the compressed file.
Is my document uploaded anywhere?
No. The file is opened, rebuilt and handed back entirely inside your browser. That matters here more than for most tools, since the documents people need to shrink are usually the ones they are about to email to a bank, a landlord or a government form.