How this tool works
Pages are copied out of each document and appended into a new one with pdf-lib, so nothing is re-rendered and nothing is re-compressed. Merging a PDF is lossless — unlike printing several documents to a single PDF, which rasterises or re-encodes everything it touches and is the usual reason a merged file looks worse than its parts.
Files are merged in the order shown, which you can rearrange or prune before running, and the output filename is yours to set. Each document is opened with encryption ignored where possible; one that cannot be read is named in the error rather than failing the batch anonymously. At least two files are needed.
Getting the order and the contents right
- Selection order is not always what you expect: check the list and move items into place before merging rather than discovering the order in the finished file.
- Name files so they sort correctly: 01, 02, 03 rather than 1, 2, 10, if you plan to rely on how your file picker orders them.
- Page-level attributes travel with the pages: rotation, page size and annotations come across as they were. Mixed page sizes in means mixed page sizes out.
- Document-level things do not: bookmarks, form fields and the metadata of the source files belong to the documents rather than the pages, and a merged file starts fresh.