Merge files into one PDF
Visually combine and reorder pages, merge multiple PDF files. Alternate and mix odd and even page from separate files.
Split PDF files
Split documents by pages. Extract separate documents. Split by size, bookmarks or text occurrences. Divide two page layout scans
Convert PDF files to Office and image formats
Convert PDF files to Word, Excel and to image. Convert images to PDF file
Reduce the size of PDF files. Optimize images and other resources
Edit PDF files
Add, edit or move text in your PDF. Change the font type, size and style. Insert, reorder, move or delete pages.
Add signature, highlight text and shapes
Apply PDF passwords and restrictions
Add copy and edit protection to a PDF. Include a password to protect your PDF from unapproved access
Add image or text watermark to PDF documents
Convert PDF text and images to grayscale
Trim PDF margins, adjust visible page area, change PDF page size
Its free but come with some restrictions like Docs up to 50Mb and 200 pages, Compress files up to 100Mb and Images up to 5Mb still it is worth it. Download it from https://www.sejda.com/desktop. It is available for Mac, Windows, and Linux