More than 30 years after Adobe came up with it, the PDF file—portable document format—remains essential for archiving, sharing, and publishing. It's a file type that can be opened by just about anyone on virtually any mobile or desktop device, while preserving the formatting, colors, and layout of the original document.Given the ubiquity and popularity of the PDF, it's no surprise that commercial PDF software tools are in high demand. But you don't necessarily have to pay to process these documents, especially for basic editing operations.A host of PDF tools are available on the web that will let you quickly and easily manipulate your documents for free (with more advanced features and usage limits available for a price). There's nothing to download, nothing to install, and nothing to pay, and they're perfect for small-scale edits.We've picked three of the best online PDF app suites below, together with three common tasks you can do with them. While these sites are all well established and reputable, use some common sense with the documents you share. Be wary about using a cloud service for editing files containing sensitive info.Edit PDFs With TinyWowTinyWow lets you edit your PDFs in numerous ways.