A Python script to batch compress PDF files on Windows, MAC, and Linux. Make sure gs and Python are in PATH before running this script.

pdfcompress.py

from __future__ import print_function
import os
import subprocess

root = "."

try:
   os.mkdir('compressed')
except FileExistsError:
   pass   
   
for file in os.listdir(root):
      if file.endswith(".pdf"):
         filename = os.path.join(root, file)
         arg1= '-sOutputFile=' + './compressed/' + file
         print ("compressing:", file )
         p = subprocess.Popen(['gs', '-sDEVICE=pdfwrite', '-dCompatibilityLevel=1.4', '-dPDFSETTINGS=/screen', '-dNOPAUSE', '-dBATCH',  '-dQUIET', str(arg1), filename], stdout=subprocess.PIPE).wait()

Complete tutorial here: https://www.ilovefreesoftware.com/02/tutorial/how-to-batch-compress-pdf-files-using-ghostscript.html

General command: gswin64 -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/screen -dNOPAUSE -dBATCH -dQUIET -sOutputFile=Output.pdf Input.pdf

gswin64 -q -dNOPAUSE -dBATCH -dSAFER -dOverPrint=/simulate -sDEVICE=pdfwrite -dPDFSETTINGS=/ebook -dEmbedAllFonts=true -dSubsetFonts=true -dAutoRotatePages=/None -dColorImageDownsampleType=/Bicubic -dColorImageResolution=150 -dGrayImageDownsampleType=/Bicubic -dGrayImageResolution=150 -dMonoImageDownsampleType=/Bicubic -dMonoImageResolution=150 -sOutputFile="output.pdf" "input.pdf"

gswin64c -sDEVICE=pdfwrite -o output.pdf -dCompatibilityLevel='1.4' -dPDFSETTINGS=/ebook -dNOPAUSE -dQUIET -dBATCH input.pdf

On Linux or macOS, change gswin64c to just gs