How to optimize a PDF
- Select the PDF or drop it onto the page.
- Choose your options, such as Fast Web View (linearisation) and removing unused resources.
- Click optimize. The file is rewritten by the qpdf engine running in your browser.
- Compare the before and after sizes and download the optimized PDF.
What optimisation does
PDFs that have been edited many times, or produced by basic export tools, often carry leftovers: unused fonts and images, uncompressed data, and a sprawling internal structure. Optimisation rewrites the file using the open-source qpdf engine compiled to run in your browser:
- Object streams pack the document's small internal objects together, which often saves noticeable space.
- Stream recompression re-compresses page data at the highest standard setting.
- Unused resources such as fonts and images that no page uses can be dropped.
- Fast Web View (linearisation) reorders the file so the first page can display while the rest is still downloading from a website.
Optimize PDF files before publishing them online: a linearised PDF with Fast Web View can show its first page while the rest is still downloading.
Optimize or compress?
Optimisation is lossless: every page looks exactly the same afterwards. It works best on text-heavy and repeatedly edited files. If your PDF is large because of photos or scans, you need Compress PDF, which reduces image resolution. For the smallest result, compress first and then optimize.
Good to know
Optimisation also normalises the file's structure, which can help some older viewers and print systems that struggle with complex PDFs. If a file is actually damaged, try Repair PDF. Your document is processed in your browser and never uploaded.
Frequently asked questions
Will optimizing change how my PDF looks?
No. Optimisation only changes how the data is stored. Pages, text and images look the same.
What is Fast Web View?
Also called linearisation, it arranges the file so a browser or PDF reader can show the first page before the whole file has downloaded. It is useful for PDFs hosted on websites.
Why did my file get only a little smaller?
Optimisation is lossless, so savings depend on how inefficiently the file was stored. For image-heavy files, use Compress PDF.
Is the file uploaded?
No. The qpdf engine runs inside your browser as WebAssembly, so the PDF stays on your device.