PDF merge is a tool for merging PDF files and extracting pages from PDF documents. The software provides "Merge PDF" and "Split PDF" functions. "Merge PDF" supports merging multiple PDF files or multiple pages of a single PDF file into one PDF document. There are multiple merging methods to choose from. The size of each page inside is different, and it can be set to the same size as the first sheet or A4 size; "Split PDF" supports extracting specific pages from a PDF document to form a new PDF document. At the same time, you can preview the pages separately, and there are multiple split options.