Split by page number, bookmark level, or file size; merge multiple documents; and "mix" pages from two different files.

Up to 3x faster than comparable tools, it supports batch processing and includes a portable version for USB sticks.

Compatible with older Windows versions through its desktop application. 4. PDFill FREE PDF Tools

Offers custom page ranges for splitting, easy drag-and-drop merging, and an integrated OCR tool to handle scanned documents.

PDFgear is a comprehensive PDF suite that remains completely free and ad-free. Unlike many "freemium" tools, it has no limits on file size or number of files for splitting and merging.