Why did lossless optimization only reduce my file by a small percentage?

If a PDF already contains pre-compressed JPEG images and minimal metadata, lossless reorganization cannot discard data that is not there. For larger savings on scanned files, use Strong Raster mode.

What DPI should I choose for strong compression?

110 DPI provides an excellent balance of readability and compact file size for screen viewing. Choose 150 DPI if you plan to print the document, or 72 DPI for maximum file size reduction.

Can I cancel processing if a large file takes too long?

Yes. An active Cancel button allows you to halt processing at any moment and releases allocated memory immediately.

Are my confidential PDF documents safe?

Yes. Processing runs completely on your computer inside your web browser. Nothing is ever uploaded to any server.

PDF Compressor

Runs in Browser

Compress and reduce PDF file size in your browser with lossless and raster modes.

How to Use the PDF Compressor

Upload your PDF document by dragging it into the dropzone or clicking to browse.

Choose your compression strategy: Lossless Optimization (preserves selectable text) or Strong Raster Compression (ideal for scanned documents).

For Strong Compression, select your target DPI resolution (72, 110, or 150 DPI) and JPEG quality level.

Monitor the page-by-page progress indicator as the document processes.

Compare original vs compressed file sizes, review percentage savings, and download your optimized PDF.

Understanding PDF Compressor

Government employment portals, university application forms, legal filing systems, and corporate email gateways routinely impose strict file size limits (such as 1 MB, 2 MB, or 500 KB) on PDF submissions. When a scanned contract or high-resolution brochure exceeds these caps, compressing the document becomes necessary. **Honest Browser-Based PDF Compression:** True lossless compression of existing PDF files in a web browser has technical constraints that many websites conceal. We provide two transparent compression approaches: 1. **Lossless Stream Optimization (Default):** Using `pdf-lib`, the tool inspects the document structure, strips redundant metadata, deduplicates internal font dictionaries, and re-encodes streams with modern object compression (`useObjectStreams`). This mode preserves 100% of selectable text and vector sharpness. For clean digital PDFs, savings are typically modest (5% to 20%). 2. **Strong Raster Compression (For Scanned Documents):** Scanned PDFs consist primarily of uncompressed, high-resolution scanned page photos. In this mode, the tool renders each PDF page to an offscreen canvas at your selected DPI (72, 110, or 150 DPI) and applies controlled JPEG compression before rebuilding a fresh PDF container. - **Important Notice:** Strong raster compression converts pages into high-efficiency images, meaning text is no longer selectable. This approach is ideal for scanned paper documents and receipts where dramatic size reductions (60% to 80%) are essential. If the output is ever larger than your original file, our tool alerts you honestly and offers your original file back. All processing runs locally with zero file uploads.

Frequently Asked Questions about PDF Compressor

In Lossless Optimization mode, all text remains selectable and searchable. In Strong Raster mode, pages are converted into optimized images, rendering text non-selectable.

Comprehensive Tutorial & Guide