I highly recommend SumatraPDF or MuPDF if you're after something a bit more. You may or may not need an add-on or extension to do it, but it's pretty handy to have one open automatically when you click a PDF link online.

Where other PDF merge software lacks the features, Cigati’s utility is rich in feature and function. Most web browsers, like both Chrome and Firefox, can open PDFs themselves. Cigati PDF Merger tool is the best utility. It's completely fine to use, but I find it to be a somewhat bloated program with lots of features that you may never need or want to use. Adobe created the PDF standard and its program is certainly the most popular free PDF reader out there. You can sort them by filenames‘ suffix number. Change the order of the files to be merged. Merge PDF: Combine multiple PDF files into one single PDF document. Most people head right to Adobe Acrobat Reader when they need to open a PDF. PDF Merger & Splitter is a powerful tool to merge PDF files, and extract pages from PDF documents. PDF files always look identical on any device or operating system. The reason PDF is so widely popular is that it can preserve original document formatting. The Portable Document Format (PDF) is a universal file format that comprises characteristics of both text documents and graphic images which makes it one of the most commonly used file types today.

What is the best free pdf merger online