Compress PDF
Reduce the file size of any PDF. Useful before emailing or uploading large documents.
PDFs from scanners are usually bloated, each page is a high-resolution image and file sizes balloon fast. I use this before emailing anything over a few megabytes. The difference between sending a 24 MB scan and a 6 MB one is significant when someone is checking email on a phone.
Your file never leaves your browser. No upload, no server, no account, compression runs locally using JavaScript.
How PDF compression works
PDF files grow large for several reasons: high-resolution embedded images, duplicate internal font data, redundant metadata, and unoptimized cross-reference tables. This tool uses PDF-lib to rewrite the document structure, removing redundancies and tightening the internal stream encoding. The result is a smaller file with the same content.
Compression levels
Light removes redundant metadata and optimizes the internal object structure without touching image data. Good for documents that are already reasonable in size but could stand to lose some overhead. Medium adds stream-level optimization on top of structural cleanup, the best starting point for most files. Strong applies every available optimization pass. Text and vector content are not degraded in any mode.
Text PDFs vs scanned PDFs
PDFs exported from word processors are usually already efficient, compression may only help modestly. Scanned PDFs are where compression shines. Each scanned page is effectively a photograph, and structural optimization can cut file size significantly without re-encoding the images.
After compressing
Check the output before replacing your original. For critical documents, keep the original until you've confirmed the compressed version looks correct. The status indicator will show how much size was saved.
Privacy
No file is sent anywhere. The entire process runs inside your browser tab. This is especially important for PDFs containing sensitive information, tax documents, medical records, legal agreements.
Frequently asked questions
How much will it reduce file size?
It depends heavily on the source. Text-based PDFs may see 10–30% reduction. Scanned image PDFs often compress by 40–60% at the medium setting. Results vary by document.
Will text remain selectable after compression?
Yes. Compression only affects the file structure and encoding, it does not convert text to images. All text remains selectable and searchable.
My PDF is still large after compression, what now?
If your PDF contains many high-resolution scanned pages, there's a ceiling to structural compression. For dramatic size reduction, the images themselves need to be re-encoded at lower resolution, which is a more destructive process this tool avoids to preserve quality.
Can I compress a locked PDF?
No. Remove the password protection first, then compress.