Processed in browser
What “processed in browser” means
- Your file is never sent to a server.
- The work happens only in your browser's memory.
- Refreshing or closing the page discards the work in progress.
- Files you download stay on your device.
- Requests for ads and site resources are separate from your file — they never carry it.
Compress PDF — Honest About How Much It Shrinks
Sometimes you need to shrink a PDF because of an email attachment cap or a submission system's size limit. But there are clear limits to what compression can do in the browser, so this tool doesn't promise exaggerated reductions.
On this page
Limited support — check the result
This tool works, but some elements can be lost or laid out differently. The limits below are the ones we know about.
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The first method, structure optimization, reorganizes the objects inside the document and clears out unused data. Text and vectors are preserved, but a well-built document may barely shrink.
The second method, image rebuilding, redraws each page as a picture. Files that are mostly images, like scans, shrink a lot, but text selection and search become impossible, so check your use case before choosing it.
How to use
Upload the PDF
The original size is shown. That value is the baseline for comparison after compression.
Choose method and strength
Pick lossless structure optimization or image rebuilding, and if you chose rebuilding, set strength to low, recommended, or high.
Compare the result and save
The original size, result size, and the amount and percentage saved are shown as real measurements. If it got bigger instead, it tells you that plainly too.
Key features
Two clearly separated methods
The quality-preserving method and the size-reducing method are offered separately, not mixed, so the result is predictable.
Measurements only
Instead of phrases like "up to 90% smaller," it shows only the actual bytes and percentage reduced for this file.
Tells you when it doesn't help
If the result is larger than the original or barely different, it recommends keeping the original.
Upfront quality-loss warning
The image rebuild method explains on screen exactly what information is lost the moment you select it.
Limits of this tool
- Lossless structure optimization can be close to 0% depending on the document.
- The image rebuild method makes text selection, search, and copying impossible.
- Big gains are hard to expect on already-optimized PDFs or text-heavy documents.
- Lossy compression at the level of professional tools (like Ghostscript) was not adopted due to licensing.
When to use it
Meeting an email attachment cap
When an attachment is blocked by a few megabytes, structure optimization alone sometimes gets you under the limit.
Archiving scanned material
Image rebuilding is effective when turning a high-resolution scan into a viewing copy.
Documents for the web
Lower the size before publishing to reduce the data usage of people who download it.
How are your files handled?
Your files stay on your device.
Compression runs in your browser too. The image rebuild method goes through drawing pages on screen, but those images also exist only in memory.
Selected files open only in your browser's memory, and results are handed straight to your device when you save. Close the tab and any remaining data is gone with it. See the Privacy Policy and File Retention Policy for details.
Related reading
- What to check when your attachment hits the size limitDon't reach for the compress button first. How mail size limits actually work, which files can shrink and which can't, and how to split a send politely.
- Photo or PDF? Choosing the format for document submissionsID copies, bank statements, receipts: when JPG is the right upload, when PDF is, and when several pages should become one file.
- Scans too big? Fix it at the scanner, not afterwards300dpi or 600? Color or grayscale? A few scanner settings decide whether you'll ever need to fight with compression again.