Free PDF Compressor
Shrink your PDF for email attachments, portal uploads, or storage. Choose from three compression modes: Fast (strips metadata and compresses streams), Standard (re-encodes with optimized compression), or Maximum (rasterizes pages to images at reduced resolution for the smallest possible output). All processing happens in your browser — your files never leave your device.
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Your file never leaves your device
🔒 Your files never leave your device — all processing happens in your browser.
Frequently Asked Questions
Are my PDF files uploaded to a server?+
No. All compression happens inside your browser using pdf-lib and the HTML5 Canvas API. Your files never leave your device — safe for sensitive documents.
What compression modes are available?+
Fast mode removes metadata (author, creator, keywords) and compresses content streams using flate compression — good for PDFs with uncompressed or loosely compressed content. Standard mode performs a full re-save with all optimizations enabled. Maximum mode rasterizes each page to a JPEG image at reduced DPI — produces the smallest possible files but converts text to images.
How much can I reduce the file size?+
It depends heavily on the original PDF. Text-heavy PDFs with uncompressed streams can shrink 20-40% with Fast/Standard mode. PDFs that are already well-compressed may show little reduction. Maximum mode (rasterize) can reduce almost any PDF by 60-90%, but text becomes non-selectable.
Will Maximum mode make the text unselectable?+
Yes. Maximum mode renders each page as a JPEG image, then assembles those images into a new PDF. The visual appearance is preserved but the text layer is lost. Use this mode only when file size is the top priority and text searchability is not needed. For searchable output from a rasterized PDF, use the PDF OCR tool afterward.
Why did my file size barely change?+
If the original PDF is already well-compressed (e.g., exported from Acrobat or a modern PDF creator), there is limited room for further reduction with Fast or Standard mode. In this case, use Maximum mode for a significant size reduction, or accept that the file is already optimized.
Is there a file size limit?+
No artificial limit. Processing happens locally in your browser. Very large PDFs (100+ MB) with Maximum mode may take a minute or two on older devices.
How PDF Compression Works — and When Each Mode is Right
PDF compression is more nuanced than image compression because PDFs are containers for multiple types of content: text, vector graphics, fonts, and raster images. The right compression approach depends on what your PDF primarily contains and whether you need the text to remain selectable afterward.
Fast Mode — Metadata Removal
Fast mode strips the document's metadata fields (author, creator, producer, keywords, title, subject) and re-saves using pdf-lib's default stream compression. PDFs often carry kilobytes of metadata that is irrelevant to the recipient. For PDFs already exported with good compression, this mode may only reduce the file by 5-15%, but it takes under a second and preserves full text and vector fidelity.
Standard Mode — Full Re-save
Standard mode performs a complete re-save with object stream compression enabled. This consolidates fragmented objects, removes deleted content that still occupies space in the cross-reference table, and applies flate (zlib) compression to all content streams. PDFs that have been repeatedly edited — for example, a contract modified multiple times in Acrobat — often contain significant "dead weight" that standard mode eliminates.
Maximum Mode — Rasterize at Reduced DPI
Maximum mode renders each page to a JPEG image using PDF.js at the DPI you select, then assembles those images into a new PDF using jsPDF. This consistently produces 60-90% size reduction because JPEG compression is far more efficient than PDF's internal formats for mixed content. The trade-off: all text becomes part of the image and is no longer selectable, searchable, or copyable. Use this mode for archiving, printing, or sharing when file size matters more than text functionality. If you later need searchable text, run the result through the PDF OCR tool.
After Compressing: Protect or Send
If the compressed PDF will be shared externally, consider running it through the PDF Password Protector to restrict opening to authorized recipients. If the file is still too large, use the PDF Splitter to break it into smaller sections.