For each visible output group, the tool creates an empty PDF, copies the selected page objects and their referenced resources, then serializes the result. A selected-pages plan produces one file. Fixed chunks and one-page mode repeat that process for each consecutive group, then package multiple files in one stored ZIP. The ZIP changes delivery only; it does not compress or alter the PDF bytes. Because shared fonts or images may be copied into several outputs, their combined size can exceed the source size.
A split result is a new document
PDFSplit copies selected visible pages into newly serialized PDF files; it does not cut bytes out of the original container. Document-level metadata, outlines, page labels, embedded files, portfolios, scripts, open actions, optional layers, tagged structure, PDF/A or PDF/X claims, usage rights, encryption, incremental history and digital signatures may not carry across. Forms, links and annotations can depend on shared resources. Keep the source and never describe an output as signed, certified, archival, compliant or evidentiary merely because the pages look correct.
Inspect every downloaded output
Open the exact downloaded PDF files in the reader used by their destination. Compare the first and last page of every requested range, total page counts, visible order, rotation and crop boxes. Test hyperlinks, annotations, form controls, fonts, reading order and accessibility where they matter. A successful local operation proves only that the current browser produced files with the reported page counts and byte sizes. It cannot prove semantic completeness, destination acceptance, identity, signature validity, legal filing, regulatory compliance or archival quality.