Compress PDF Online
Reduce PDF file size without sacrificing readability or image sharpness. Free, fast, and secure.
Select PDF File
or drag & drop PDF here
About Compress PDF Online — Free PDF Compressor
KAOpdf Compress PDF is a free online tool that reduces the file size of your PDF documents without losing quality. Whether you need to compress PDF for email, reduce PDF size for WhatsApp, or shrink a PDF to meet upload limits, our high-performance compressor handles it all instantly with industrial-grade engines. All files are encrypted during transfer and automatically deleted from our server within 2 hours — your documents are never permanently stored. No sign up, no subscription, no watermark, and no file size limit. Simply upload, compress, and download in seconds.
How to Use Compress PDF
Upload Your PDF File
Select the PDF you want to compress from your computer, phone, or tablet. No account or sign up needed.
Automatic Optimization
Click 'Compress PDF' and our high-performance engine optimizes fonts, removes redundant objects, and cleans streams to shrink the file size.
Download the Smaller PDF
Instantly download your compressed PDF file — ready to send via email, WhatsApp, or upload to any platform.
Specifications & System Limits
TLS 256-bit Encryption
Files are temporarily uploaded to our private microservice via encrypted channels and purged permanently within 2 hours.
Super Fast & Reliable
Instant high-speed conversion with ultra-low latency. Never wait in arbitrary processing queues.
100% Free & No Watermark
All tools on KAOpdf are completely free with no watermarks, no file limits, and no account registration required.
Frequently Asked Questions (FAQ)
How do I reduce PDF file size for email?+
Upload your PDF to KAOpdf Compress PDF, click 'Compress PDF', and download the smaller file. The compressed PDF will be significantly smaller and ready to attach to any email.
Does compressing a PDF reduce quality?+
KAOpdf optimizes the PDF's internal structure, removes redundant data, and cleans metadata without aggressively recompressing images. This means text and graphics remain crisp while file size is reduced.
Are my files uploaded to a server when I compress PDF?+
Your files are transmitted via an encrypted TLS/HTTPS connection, processed securely in isolated memory, and automatically deleted from our server within 2 hours. We never inspect or permanently store your documents.
Is there a file size limit for compression?+
There is no strict file size limit on our end — the only limit is your device's available memory. Most PDFs under 500MB compress without issues.
Can I compress a PDF without losing quality?+
Yes. KAOpdf's compression algorithm focuses on structural optimization rather than image degradation, so quality is maintained while file size is reduced significantly.
Is KAOpdf Compress PDF completely free?+
Yes. The PDF compressor is 100% free with no watermark, no sign up, no usage limits, and no hidden fees.