How to Compress PDF Files Online

DevToolKit PDF Compress runs In-browser. Raster presets normally render each processed page to a canvas and rebuild the output from JPEG page images. Repack only copies the pages being processed into a new PDF and saves it with object streams.

There is no universal quality guarantee. Output size and readability depend on how the PDF was built — a scan-heavy file behaves differently from a text-exported report.

Open the original export, not a file you already compressed. Repeated passes stack quality loss with diminishing size gains.

Rename outputs clearly — report-original.pdf and report-compressed.pdf — so you never overwrite the only clean copy.

Start moderate. Aggressive raster settings shrink scans fastest but can blur small text, stamps, and chart lines.

Text-heavy PDFs with vector fonts may show little size change because most bytes are not images. That is normal — repacking alone cannot invent huge savings.

Scanned PDFs store each page as an image. Raster compression targets those bitmaps directly — expect visible trade-offs at high settings.

Text-heavy PDFs exported from Word, Google Docs, or LaTeX can retain selectable text with Repack only, although savings may be small. Maximum, Balanced, and High quality normally rebuild processed pages as JPEG images; when that result is not sufficiently smaller, the compressor can use structure repacking instead. Inspect readability and text selection in the result.

Upload or drop the file into PDF Compress. Processing stays In-browser — the file does not leave your tab for this tool.

When processing finishes, compare file size and open the document. Zoom to 100% on signatures, footnotes, tables, and any embedded photos.

If only part of a long PDF matters, split or extract those pages before compressing. Fewer pages means less work and sometimes a better size-to-quality ratio.

Remove blank or duplicate scans from the source bundle when preparing an email attachment.

Email attachments — many providers cap size near 10–25 MB. Portal uploads — school and government forms reject oversized files. Mobile sharing — smaller PDFs download faster on slow networks.

After compressing, merge multiple assignments with PDF Merge if the portal wants one file. Protect sensitive extracts with PDF Protect when required.

Original saved separately; moderate setting tried first; page count trimmed if possible; text readable at 100% zoom; charts and signatures intact; file size meets upload limit; correct filename on the version you send.

If quality is unacceptable, revert to the original and try a lighter setting or remove pages instead of re-compressing the same output.