Smart compression: auto-detects PDF type and picks the best strategy — 100% browser-based
Smart compression auto-detects PDF type: image-heavy PDFs use JPEG re-encoding for maximum reduction, while text-heavy PDFs use lossless structure optimization. All processing happens in your browser.
A PDF is a bag of numbered objects: page dictionaries, font programs, image XObjects and content streams. Text-based PDFs are already lean, so this tool uses a lossless rebuild: it strips document metadata, removes duplicated objects, re-packs the streams with FlateDecode (zlib) and groups objects into object streams with a compressed cross-reference stream. Image-heavy PDFs (scans, photos) are different: their bulk is raster data, so a lossy path re-renders every page to a fresh JPEG at the chosen quality and DPI, discarding the original image and text streams. The tool auto-detects which family your file belongs to by measuring bytes-per-page and counting image operators in the page content.
Top: text PDFs gain only a few percent from a lossless restructure. Bottom: image PDFs can lose 50–75% because their bulk is re-encoded JPEG raster.
A 12.4 MB, 40-page scanned agreement with photos, compressed at the Medium level (70% quality, 120 DPI, 0.85 scale).
To compress a PDF without uploading: select your file, choose a quality level, and the tool re-encodes images and removes redundant data locally in your browser.
FreeToolHub PDF Compress is a free browser-based tool that reduces PDF file size without uploading, no signup required.
Shrink PDF file size for email and uploads. 3 compression levels: light, medium, strong. 100% in-browser, your file stays private. Free.
The PDF Compressor is a free, browser-based tool that shrinks PDF file sizes so they fit email attachments and upload limits. It offers three compression levels — low, medium, and high — that re-encode embedded images and streamline internal PDF objects to cut weight while preserving readability. The entire process runs locally using JavaScript and WebAssembly, meaning your document never uploads to a server. That makes it a private alternative to online compressors, and because there is no remote processing queue, even large multi-megabyte files compress instantly on your own machine.
This tool is for anyone hitting file-size limits. Job seekers attaching resumes to application portals capped at 2 MB, students submitting assignments, real estate agents emailing listing packets, and office workers sending scanned contracts all benefit. If a PDF is too heavy for Gmail’s 25 MB ceiling or a government upload form, this browser-based compressor reduces it in seconds. It is especially valuable when the document is confidential, since nothing is uploaded and the file stays private throughout.
Drag a PDF into the tool or click to browse your files. Choose a compression level: low keeps maximum quality for print, medium balances size and clarity for everyday sharing, and high produces the smallest file for tight upload limits. The tool recompresses images and rebuilds the PDF locally, showing the original and new sizes side by side so you can confirm the savings. Preview the result, then download the compressed file with one click. Your source document is never modified or uploaded, keeping the workflow fast and private.
Typically 30-70% depending on content. Image-heavy PDFs compress most (a 50MB scanned document can drop to 8-15MB). Text-heavy PDFs compress less since text is already efficient. Three compression levels are available: light (lossless, ~20% reduction), medium (recompress images, ~50%), and strong (aggressive image downsampling, ~70%).
Light compression preserves all text and image quality. Medium recompresses images at 85% JPEG quality—barely noticeable. Strong compression downsamples images to 150 DPI, which is adequate for screen viewing but may reduce print quality. All compression is done in-browser—your file never leaves your device.
This tool is also known by these tasks — each link opens the same tool with a focused guide:
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