You cannot compress a PDF file when the PDF is downloaded from the web. Compress PDF on Android Device using PDF Reader — Smallpdf.com You can also go through the same process, but this time you will need to open PDF files and decompress them on your device How to Reduce PDF Size Manually on Android — Smallpdf.com Launch Tiny PDF Android App and select the PDF file to compress as well as other files to be compressed. This can be used to get rid of unnecessary text, images, etc. How to compress a PDF and reduce its size on Mac and PC Use this free PDF software to do the job for you: How to Compress PDF from Mac/PC in Office Step 1. Open your PDF file to view its contents from Windows. Step 2. Locate the section, paragraphs or lines that need to be deleted. If you are using a software like Acrobat, Adobe InDesign or Microsoft Vision, you can also use the tools to delete the text, images, and other elements to delete PDFs. Step 3. Open the Edit menu. You can also drag and drop the text, images and other elements inside the area to be deleted. Step 4. Press Command + Z to create a new page and return to Edit, then use the space available to delete the text or elements as desired, and then save the edited PDF. If you are not using any editing software, use the page's Create PDF button to create a new (empty) page of your PDF. How to Reduce PDF Size Manually on Mac/PC Using PDF Compressor 3 Step 1. In PDF Compressor 3, go to File > Save As. Step 2. Select the destination directory and file format of your PDF; select .PDF. Step 3. Then click Save As. How to Compress PDFs Offline Step 1. Install Open PDF for Windows. Step 2. Make sure that you have a recent PDF reader installed on you PC. Open the .PDF that you want to compress as well as any other PDF files that you want to compress with Open PDF. Open Acrobat Pro for free and open the Compress feature. Select the option to shrink the file. Step 3. After converting or shrinking the file, you can view its contents. To go back to an earlier size, click on the Compressed button. To revert the original size, press Backspace.