How much smaller will my PDF get?

It depends heavily on the file. Scanned pages and photo-heavy PDFs — the files that are usually largest — can shrink substantially on Recommended or Aggressive, since their size is dominated by embedded JPEG photos that this tool actually recompresses. Text-only or vector PDFs (no photos) will only see the smaller, structural gain from metadata stripping, since there are no images to touch.

Does this recompress or downscale embedded images?

On Recommended and Aggressive, yes — embedded JPEG photos are decoded, downscaled, and re-encoded at a lower quality (85% size / 60% quality on Recommended, 60% size / 42% quality on Aggressive), then written back into the same PDF. Light mode skips this and only does lossless metadata/structure cleanup. Non-JPEG image formats inside a PDF (rare — e.g. JPEG2000 or CCITT fax scans) aren't recompressed and are left as-is.

Will the text or visual quality of my PDF change?

Text and vector content are never touched — they stay pixel-for-pixel identical, since only embedded JPEG image data is re-encoded. Photos will look slightly softer on Recommended and noticeably softer on Aggressive; if a recompressed image would come out larger than the original (rare, for already-optimized images), it's left untouched instead.

What's the largest PDF this can handle?

It's limited by your browser's available memory rather than a hard cap, since the whole file — plus each image being decoded and re-encoded — is processed in memory. Most PDFs up to a few hundred megabytes work fine in a modern browser tab; very large files (500MB+) or files with dozens of large photos may slow down or fail depending on your device.

Is my PDF uploaded anywhere?

No. The file is read, recompressed, and reassembled locally using pdf-lib and the browser's own canvas/JPEG encoder — it never leaves your machine or touches a server.

PDF COMPRESSOR

Choose a PDF and pick a compression level to shrink its file size. Nothing leaves your browser.

+ Choose a PDF

Nothing uploaded — the file is compressed straight in your browser tab.

How to compress a PDF

1
Upload the PDF you want to shrink.
2
Pick a compression level — Light, Recommended, or Aggressive.
3
Click Compress PDF and review the before/after file size.
4
Download the compressed file.

Questions

How much smaller will my PDF get?: It depends heavily on the file. Scanned pages and photo-heavy PDFs — the files that are usually largest — can shrink substantially on Recommended or Aggressive, since their size is dominated by embedded JPEG photos that this tool actually recompresses. Text-only or vector PDFs (no photos) will only see the smaller, structural gain from metadata stripping, since there are no images to touch.
Does this recompress or downscale embedded images?: On Recommended and Aggressive, yes — embedded JPEG photos are decoded, downscaled, and re-encoded at a lower quality (85% size / 60% quality on Recommended, 60% size / 42% quality on Aggressive), then written back into the same PDF. Light mode skips this and only does lossless metadata/structure cleanup. Non-JPEG image formats inside a PDF (rare — e.g. JPEG2000 or CCITT fax scans) aren't recompressed and are left as-is.
Will the text or visual quality of my PDF change?: Text and vector content are never touched — they stay pixel-for-pixel identical, since only embedded JPEG image data is re-encoded. Photos will look slightly softer on Recommended and noticeably softer on Aggressive; if a recompressed image would come out larger than the original (rare, for already-optimized images), it's left untouched instead.
What's the largest PDF this can handle?: It's limited by your browser's available memory rather than a hard cap, since the whole file — plus each image being decoded and re-encoded — is processed in memory. Most PDFs up to a few hundred megabytes work fine in a modern browser tab; very large files (500MB+) or files with dozens of large photos may slow down or fail depending on your device.
Is my PDF uploaded anywhere?: No. The file is read, recompressed, and reassembled locally using pdf-lib and the browser's own canvas/JPEG encoder — it never leaves your machine or touches a server.