A short guide to lossless PDF merging — how to preserve bookmarks, form fields and digital signatures when combining files, and what to avoid.
Open PDFWix's Merge PDF tool, drop your files in the order you want them, and click Merge. The output is a byte-identical concatenation — no re-rendering, no quality loss.
PDFWix preserves the outline (table of contents) of each source file and stitches them under a new top-level entry per file, so you keep navigation in the merged document.
Form fields are renamed if duplicates exist across files. Digital signatures are preserved but technically invalidated — that's a property of the PDF spec, not PDFWix.