How to compress a PDF
- Choose one PDF file.
- Select a mode: Optimize for lossless; Balanced/Strong/Custom for bigger savings on scans and photos.
- For Custom, set max DPI, JPEG quality, and optional grayscale.
- Click Compress PDF and download the result.
About this tool
Compress PDF reduces file size so documents are easier to email or upload. ReallyFreePDF offers Optimize (lossless structure optimization with qpdf in WebAssembly) and lossy modes (Balanced, Strong, Custom) that rasterize pages and re-encode as JPEG at a chosen DPI — useful for large scanned PDFs.
Engines run locally. PDF contents are not uploaded for processing. See Privacy and About.
FAQ
Why did Optimize only save a tiny amount?
Optimize recompresses structure and streams without re-encoding photos. Already-tight or image-heavy PDFs may shrink very little. Use Balanced or Strong for scans.
Will lossy modes reduce quality?
Yes — that is the trade-off for large size wins. Pages become images; text is no longer selectable. Strong is more aggressive than Balanced.
Is Compress free? Any daily limit?
Yes, free with no daily quota. Large files may take time and memory; you can Cancel during lossy runs.
Does my file get uploaded?
No. Processing stays in the browser. CDN requests are for site code and WASM engines only.
Can I keep color on Strong?
Yes. Strong uses lower DPI and JPEG quality but keeps color. Grayscale is only applied when you enable it under Custom.