Compress PDF Online
Instantly reduce your PDF file size in your browser – no uploads, no server, 100% private. Supports files up to 25 MB.
Drag & drop your PDF here
Max 25 MB · Processed locally, never uploaded
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Compression Level
How to Use This PDF Compressor?
Using our PDF compressor is straightforward. Drag and drop your PDF onto the upload area, or click to browse for a file. Select your desired compression level – Low for high quality, Medium for a balanced result, or High for the smallest possible file size. Hit Compress PDF and your optimised file is ready instantly.
The tool displays your original file size, the compressed file size, and the exact percentage saved. Once complete, click Download to save the compressed PDF directly to your device – all processed in real time using pure JavaScript, with no data ever leaving your browser.
What is a PDF Compressor?
A PDF compressor is a free online tool that lets you instantly reduce the file size of any PDF document – without losing readability. Whether you need to email a large report, upload a file that exceeds a size limit, or simply free up storage space, our tool handles it all in seconds, with no sign-up or downloads required.
Our online PDF compressor is especially useful when you need to share documents quickly. Rather than purchasing expensive software like Adobe Acrobat Pro, our compress PDF tool runs entirely in your browser and delivers results in three adjustable compression levels.
Why Use Our Compress PDF Tool?
Many online tools upload your files to remote servers, raising privacy concerns. Our compress PDF online tool goes much further – all processing happens locally on your device using PDF.js and pdf-lib. No file is ever transmitted, stored, or shared. It is completely private and secure.
It also supports all three compression levels to give you full control over the quality-versus-size trade-off. Whether your PDF is a scanned document, a presentation, or an image-heavy report, our reduce PDF size tool handles them all and delivers meaningful compression every time.
Common Uses of a PDF File Compressor
People use a PDF file compressor for a wide variety of reasons – sending documents by email when attachment size limits apply, uploading files to government portals or job application systems, reducing storage on phones and laptops, sharing large brochures or catalogues faster, and archiving scanned documents more efficiently. Businesses use it daily to keep workflows fast and file systems tidy.
Frequently Asked Questions
How accurate is this PDF compressor?
Our PDF compressor uses PDF.js to render each page at your chosen quality level and pdf-lib to rebuild the document. The output is a fully valid, readable PDF. Compression ratios depend on the content – image-heavy files compress the most, while text-only PDFs see moderate reductions. The exact savings are shown after every compression.
Is my PDF file kept private?
Yes, completely. Your PDF never leaves your device. The entire compression process runs locally in your browser using JavaScript. Once you close the tab, no trace of your file remains anywhere. This makes it safe to compress confidential documents such as contracts, invoices, passports, and medical records.
What is the difference between the three compression levels?
Low (High Quality) renders pages at high resolution with 90% JPEG quality – ideal for printing or professional use. Medium (Balanced) reduces resolution and quality moderately, giving a strong size saving while keeping the document visually clear for reading and sharing. High (Smallest Size) applies aggressive downscaling and 50% JPEG quality to achieve the smallest possible file, best for archiving or quick uploads where file size matters most.
Why didn't my PDF compress much?
PDFs that contain mostly text with very few embedded images, or files that were already compressed by other software, will see smaller reductions. Files containing many high-resolution photographs or scanned pages typically achieve the greatest savings. Try switching to the High compression level for maximum size reduction.
What is the maximum file size I can compress?
This tool supports PDF files up to 25 MB. Because all processing happens in your browser, very large or complex files may take a little longer on slower devices. For files above 25 MB, consider splitting the PDF into smaller parts first using a PDF splitter tool, then compressing each part individually.