Merging PDFs sounds simple: drop a few files in, hit combine, done. But the method you choose matters. A bad merge can turn crisp, selectable text into a blurry photograph, break internal links, and quietly strip out bookmarks and form fields. Here is how to combine documents the right way.

Why merging can go wrong

The most common mistake is re-rendering pages to images and then stitching those images back into a PDF. It feels safe because nothing looks out of place — until you try to select text, copy a paragraph, or click a link and realise the whole document is now a picture.

  • Rasterised pages: text becomes pixels, so search and copy stop working.
  • Lost bookmarks: the table of contents disappears.
  • Broken form fields: fillable forms become flat.
  • Bigger files: image-based pages are far heavier than the original vector text.

The right way to merge

A proper merge keeps each page exactly as it was — vector text, links, bookmarks and all — and simply appends the pages from one document to the next. This is called a page-level merge.

  1. Add your PDFs in the order you want them to appear.
  2. Reorder by dragging if needed.
  3. Combine at the page level, preserving the original content streams.
  4. Download a single, clean PDF.
Good merging is invisible: the result should look and behave exactly like the source files, just in one cover.

Try it with SELKATDocs

SELKATDocs merges PDFs in your browser using a page-level approach, so text stays selectable and your file never leaves your device unnecessarily.

Try the SELKATDocs Merge PDF tool →

A few tips

  • Check page sizes first — mixing A4 and Letter can look odd.
  • Remove blank pages before merging to keep the result tight.
  • If a file is encrypted, you will need its password to include it.

Merge carefully and your combined document will be just as sharp as the originals.