Compress PDF
Make a PDF smaller by recompressing the photos inside it. Text stays text. It runs in your browser, so the file is never uploaded.
This shrinks the photos and scans embedded in the PDF. It does not touch text — a text-only PDF is already small and this tool will say there is nothing worth compressing rather than pretend to help.
Most oversized PDFs are oversized because of the photos or scanned pages inside them, not the text. This finds those images and recompresses them — the text stays exactly as it was, still selectable and searchable, which a render-and-rebuild compressor can't promise.
How the compression works
A PDF gets heavy because of the pictures in it, not the text. The page opens the file with pdf-lib and walks through every page, including shared drawings that several pages use, looking for embedded JPEG pictures. Each one it can read is decoded in the browser, scaled down if it is larger than the level allows, and saved again as a JPEG at lower quality, then put back into the file only if the new version is actually smaller. The three levels set the quality and the longest side: Light is 80% and 2000 pixels, Balanced 65% and 1600, Strong 50% and 1200. A picture is never enlarged. Text, fonts and vector drawings are not touched, so text stays selectable and searchable, and the file is not turned into page images.
What it leaves alone, and the limits
Only JPEG pictures in ordinary RGB or grey colour, of at least 20 KB, are recompressed. Pictures stored another way (many scanning apps save pages in black-and-white or lossless formats), and CMYK, indexed or colour-profiled pictures, are skipped, so a scan can come back unchanged; the page then says nothing here was worth compressing and gives no file. The result is lossy: recompressed photos lose some detail, and more at Strong. Bookmarks, links, form fields, the title and the author stay. One PDF at a time, up to 100 MB. A PDF that asks for a password to open is refused with a message; one that only restricts printing or copying is processed, and the result has no restrictions. Large files can take a while, and there is no progress bar.
How to use it
- Add the PDF.
- Pick a compression level.
- Press Compress PDF and download the result.
Why use this tool
Completely private
Everything runs inside your browser. Your files and text are never sent to a server.
Free, with no limits
No sign-up, no watermarks and no cap on how many times you can use it.
Instant results
There is no upload or queue to wait for, so results appear as fast as your device can work.
Works on any device
Runs in any modern browser on phone, tablet or desktop. Nothing to install.
Frequently asked questions
- How much smaller will my PDF get?
- It depends on what is inside. A PDF made of large photographs or camera-quality pages can shrink a lot; one that is mostly text, or whose pictures are already small or stored another way, may not shrink at all. The result shows the size before and after, and the page gives no file when it could not make one smaller.
- Which level should I choose for email?
- Start with Balanced, the default: it limits pictures to 1600 pixels on the long side at 65% quality, which looks fine on a screen. Use Strong (1200 pixels, 50%) when the file is still over the attachment limit, and Light (2000 pixels, 80%) when the pictures matter more than the size.
- Can I choose a target size, such as 1 MB?
- No. The levels set picture quality and size, not a final file size, so you cannot ask for a number of kilobytes. If the first result is still too large, run the original again at a stronger level.
- Why does it say there's nothing to compress?
- That means the PDF has no images it can confidently recompress — a text-only document, for instance, which is already small. Rather than rasterise the whole page to manufacture a smaller file (which would break the text), it says so plainly.
- Will my document still look right?
- Yes. Layout, fonts and every other piece of content are untouched — only the compressed image data inside is replaced with a smaller version.
- Does the text stay selectable afterwards?
- Yes, completely. Nothing about the text layer changes. This is the entire reason this tool works the way it does rather than rendering pages to pictures.
- Which images does it skip?
- Anything it isn't fully confident is safe to touch — images already using an indexed or unusual colour space, or ones so small that recompressing them wouldn't help. It only acts where it can be sure of the result.
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