How to Compress a PDF Online for Free (No Sign-Up)
Compress one PDF up to 100 MiB in your browser. Learn which lossy preset to choose, what stays unchanged, and why file-size savings vary.
What this compressor changes
Large embedded images can account for much of a PDF's size. PDF Compressor tries to shrink supported images with lossy JPEG recompression and downsizing, then saves the document using compact object streams. It runs locally in a JavaScript worker, not WebAssembly, and does not upload your PDF.
Text, fonts, page layout, and document metadata are preserved. Pages are not rasterized: existing selectable text stays text, while scanned text remains part of an image. Compression does not add OCR, remove metadata, or sanitize sensitive content.
1. Choose one PDF
Open PDF Compressor using the button below, then choose or drop one non-empty PDF up to 100 MiB (104,857,600 bytes). There is no batch mode. Keep your source file so you can compare the result.
Encrypted PDFs, including permission-restricted files, are rejected. Documents with populated digital signatures are also rejected because compression would invalidate those signatures. Use an unencrypted, unsigned copy you are authorized to edit. Empty signature fields alone do not trigger rejection; signature authenticity is not checked.
2. Choose a compression preset
Start with Balanced, the default. Choose Light to retain more image detail, or Strong for more aggressive compression. All three presets are lossy: they can change visible image detail and color, even though text is preserved.
The presets use JPEG quality settings of 85%, 65%, and 40%, with maximum image dimensions of 2,000, 1,600, and 1,200 pixels respectively. These settings are not promised file-size reductions, and Strong is not guaranteed to reach an email or upload limit.
3. Run compression
Click Compress PDF and wait for the result. Processing time and memory use depend on the document and your device, even below the 100 MiB cap. You can cancel; the source stays selected. A job that takes longer than 60 seconds times out, so try a smaller PDF if needed.
Unsupported images are left unchanged rather than approximated. This includes many images with color profiles, masks, or complex encodings. Images may also be skipped because of safety limits, decoding errors, or a lack of size savings.
4. Review and download
Compare the original and output sizes and the counts of optimized and unchanged images, then download. If the complete output would be equal in size or larger, the tool returns your original PDF byte for byte. Text-heavy and already optimized documents may not shrink at all; there is no target-size guarantee.
Open the downloaded PDF and inspect images and small details before sharing. Use Adjust compression to retry with another preset, or New file to process another PDF. If the result still exceeds your destination's limit, consider re-exporting from the source with smaller images or splitting the document where permitted. Review sensitive content and metadata separately: compression leaves them in place.
Try it free — PDF Compressor
Compress one PDF up to 100 MiB locally with three lossy image presets. Text is preserved; output is never larger than the original.
Open PDF Compressor