Use an online PDF compressor
Open the PDF in Adobe Acrobat and use the compress or optimize feature
Reduce image quality inside the PDF
Remove unnecessary pages from the PDF
Convert images in the PDF to grayscale
Lower the resolution of embedded images
Remove unused fonts and metadata
Save the PDF with “Optimize for size” or “Reduced size PDF”
Print the PDF to a new PDF using a smaller file size setting
Use a desktop PDF editor with compression tools
Split a large PDF into smaller files
Compress the PDF with command-line tools like Ghostscript
Re-export the PDF from the source file with lower quality settings