Compress PDF
Shrink one or more PDFs. Choose how much quality you want to trade for size.
Drop PDFs here
or click to browse files
How to Compress PDF
Large PDF files are frustrating — too big to email, too slow to upload, and rejected by web forms. ZimaPDF's Compress tool reduces file size with multiple quality presets, all processed privately inside your browser without any server upload.
Pick one or more PDF files
Select documents from your device by dragging them into the upload zone or clicking to browse. You can process multiple PDFs in a single batch.
Choose a compression level
Select a preset that fits your needs: "Lossless" removes hidden structural overhead without touching image quality; "Low", "Medium", and "High" progressively reduce image resolution for smaller files; "Extreme" aggressively shrinks every image; "Scanned" is optimised for PDFs created from physical scanners or phone cameras.
Click Compress & Save
Processing runs entirely in your browser's memory — no upload, no waiting. You'll see exactly how much smaller your file became (e.g., '62% smaller') and can download immediately.
Why use ZimaPDF for compress pdf?
Multiple Compression Levels
From a gentle lossless pass that removes structural bloat, all the way up to extreme image downscaling, you have full control over the quality-versus-size trade-off.
Batch Processing
Drop multiple PDFs at once and compress them all in a single operation. The results are packaged into a convenient ZIP file for download.
See Exact Savings Before Downloading
After compression, ZimaPDF shows you both the original and new file sizes so you know exactly how much space was saved before you commit to downloading.
No Quality Surprises with Lossless Mode
Choose Lossless mode and your document's visual appearance is guaranteed to be identical — only redundant internal data is removed.
Frequently asked questions
Are my files uploaded to a server when I compress?
No. All compression runs locally in your browser using client-side JavaScript. Your PDF files are never sent over the network, so your confidential documents remain completely private.
Will compression reduce image quality?
It depends on the preset you choose. The Lossless mode only removes internal structural overhead and never touches image quality. The Low, Medium, High, and Extreme modes do reduce image resolution — but you can preview the exact reduction in file size before downloading.
What is the difference between Lossless and Extreme compression?
Lossless removes hidden data such as duplicate objects and unused streams without affecting any visible content. Extreme aggressively re-encodes every image in the document at a very low resolution, which produces the smallest possible file size but can cause images to appear blurry.
Why is my PDF still large after lossless compression?
If a PDF is large mainly because of high-resolution images, lossless compression won't shrink it much since it doesn't touch image data. Switch to Medium or High compression in that case to target the images directly.
Can I compress multiple PDFs at once?
Yes. You can drop several files into the upload zone simultaneously and compress them all in one batch. The results are downloaded as a ZIP archive.
What is the Scanned preset for?
Scanned mode is optimised specifically for PDFs that were created by scanning physical paper with a scanner or phone camera app. These files tend to have very large, unoptimised images, and the Scanned preset is tuned to reduce them efficiently while keeping text legible.