In my desperate search for ways to optimize PDF files, I’ve found that there aren’t many free options. Although there are a lot of shareware programs, there are also, thankfully, a few free programs can help you reduce a PDF file size.
Irfanview & GhostScript [Windows & Possibly Linux]
If you don’t have Irfanview, you should really consider downloading it. It’s a much better and lightning fast alternative to the default image viewer in Windows, supports countless plugins that allow it to be extremely versatile, and converts images to different file types. You can use it to add borders and watermarks to your photos, and batch process many images at a time. You can also view PDF files, provided you download GhostScript first.
Once you have Ghostscript installed, you can use Irfanview (portable version will work as well) to view PDF files and save them as new files. You’ll get a box on the right of the Save As dialog to choose compression levels.
You can choose to save with lossless, best, high, medium, and ‘dump’ quality. In my tests, Irfanview reduced a 14MB PDF file to 8MB using the high-quality setting in Compression, while the lossless and best quality settings produced files bigger than the original size.
PrimoPDF is a desktop application that allows you to create PDF files from image files and documents.
It installs itself as a virtual printer, which makes optimizing PDF files a matter of opening the files and printing them with PrimoPDF, though you can also drag and drop documents to the PrimoPDF desktop shortcut. From there, you’ll get a dialog box, where you can choose the document quality.
For the smallest file size, choose the Screen setting. Pressing Create PDF starts the conversion.
Free PDF Compressor (version 1.12) [Windows]
This program is now shareware but the link provided leads to the last freeware version. It is pretty much just an executable that does a decent job at reducing PDF file sizes. In my tests, this program managed to reduce a 50MB PDF file to 45MB, with the maximum compression level, at an impressive speed (almost instant conversion).
Neevia’s PDFCompress [Web-Based]
PDFCompress is a simple web app that takes any PDF files smaller than 5MB and compresses them according to the presets you chose (low, medium, high and maximum). Maximum compression means the quality will be approximately a 10 in a scale of 100. In my test with a 3MB file and maximum compression, the optimized file was about 9% smaller, with no visible quality loss.