PDF Compressor
Reduce PDF file size in three clicks. Choose your compression level, compress, and download — no upload, no sign-up, runs entirely in your browser.
Drop your PDF here
or click to browse
What is PDF compression?
PDF files can be large because they contain high-resolution images, embedded fonts, and other resources. Compression reduces file size by re-encoding page content at a lower resolution or quality — making files easier to email, upload, or store without significantly affecting readability at normal viewing sizes.
How this tool compresses
Each page is rendered to a canvas at the chosen resolution scale, then saved as a JPEG image at the chosen quality. The images are assembled back into a valid PDF using pdf-lib. This is the same approach used by most online PDF compressors — it is fast, works entirely in the browser, and reliably reduces file size.
Choosing a compression level
Low renders at 2× scale with 85% JPEG quality — the best output quality with moderate size reduction, suitable for documents you need to print. Medium uses 1.5× scale and 70% quality — a good all-purpose default. High uses 1× scale and 50% quality — the smallest files, ideal when reducing size is the priority over visual fidelity.
How to use
- Upload a PDF by dropping it onto the upload area or clicking to browse.
- Choose a compression level — Low for best quality, High for smallest size.
- Click Compress PDF. The tool processes each page in your browser.
- Review the original size, compressed size, and percentage saved.
- Click Download compressed PDF to save the file.
Examples
- Simple: A 4 MB product brochure with large photos needs to be emailed. Use High compression to bring it to ~800 KB — well within most email attachment limits.
- Developer workflow: A CI pipeline uploads scanned PDF reports to S3. Run the compressor at Medium level before upload to cut storage costs and speed up page loads for end users downloading the reports.
- Edge case: If the compressed file is not smaller than the original, the PDF is already highly optimised (e.g. it was previously compressed or contains very little image content). Try a higher compression level, or accept the original file as-is.
Your PDF is compressed entirely in your browser using PDF.js and pdf-lib — no file is uploaded to any server.
Frequently Asked Questions
- How does browser-based PDF compression work?
- Each PDF page is rendered to a canvas element using PDF.js, then encoded as a JPEG image at the chosen quality level. A new PDF is built from those compressed images using pdf-lib. The result is a smaller file because JPEG compression discards visual detail that is often imperceptible at normal viewing sizes.
- Will compressed text still be selectable?
- No. The compression process converts each page to an image, so text in the resulting PDF is not selectable or searchable. This is a trade-off inherent to image-based compression. If you need selectable text, use Low compression which preserves the highest image quality.
- Is my PDF uploaded to a server?
- No. The entire compression process runs in your browser using PDF.js and pdf-lib. Your file is never uploaded to any server or transmitted anywhere.
- Which compression level should I choose?
- Low compression is best for documents you need to print or share at high quality. Medium is a good default for general use. High compression is ideal when file size matters most, such as email attachments or web uploads, and a slight quality reduction is acceptable.