Use Adobe Acrobat: Open Acrobat, go to Tools, select Combine Files, add all PDFs, arrange them, and click Combine
Use Preview on Mac: Open one PDF in Preview, show thumbnails, drag other PDFs into the sidebar, then save as one file
Use free online tools: Upload all PDFs to a trusted merge PDF website, combine them, and download the merged file
Use Microsoft Word: Insert each PDF as an object or convert them first, then save or export as a single PDF
Use command line tools: Use PDFtk, Ghostscript, or qpdf to merge PDFs with a merge command
Use file manager apps: Select multiple PDFs in some apps, choose Merge or Combine, and save the result
Use browser-based PDF editors: Open a PDF editor in your browser, upload files, merge them, and export the combined PDF
Use mobile apps: Install a PDF merge app, add all PDFs, reorder them, and save as one file