If you use Ubuntu, you may have run into the frustration of trying to find a native way to annotate your PDFs, such as any of the MakeUseOf PDF manuals you know you can download for free. Unless you run some Windows program via Wine, wait for Evince's annotation features, or learn how to use the incredibly user-unfriendly PDFEdit, you're not going to have much luck. That's when you can be thankful that there are developers focused on making web-based PDF tools.
There are many PDF tools, many of them are document viewing sites 3 Websites to View Your PDFs Online 3 Websites to View Your PDFs Online Read More web How to embed a PDF document on your website Read More
Few web-based PDF tools actually offer annotation features like what you can find in Foxit FoxIt Reader - A Great Alternative PDF Reader for Linux FoxIt Reader - A Great Alternative PDF Reader for Linux Read More doesn't actually have Annotation Tools) or PDF-XChange PDF-XChange Viewer - Give this free PDF reader a second look PDF-XChange Viewer - Give this free PDF reader a second look Read More, my favorite reader with shortcuts customizable keyboard. Perhaps you occasionally use PDF files or have a PDF reader without many or no annotation features, like the 4 Very Light Alternatives to Adobe Reader 4 Very Light Alternatives to Adobe Reader Still using Adobe Reader for PDF documents? It's time to move on to an alternative PDF reader that's lightweight, starts up quickly, while keeping your documents saved. Read more SumatraPDF 100 Portable Apps for your USB Drive for Windows and macOS 100 Portable Apps for your USB Drive for Windows and macOS Portable Apps let you take your favorite software anywhere via flash drive or cloud storage. Here are 100 of them to cover all your needs, from games to image editors. Learn more or conjure up Ubuntu 6 Free Linux-Friendly Office Suites to Get the Job Done 6 Free Linux-Friendly Office Suites to Get the Job Done Read More .
No matter why you need a quick way to annotate PDF files, check out the following web-based PDF tools.
PDFEscape has been featured on our site as an excellent PDF editor and form filler with the basic features that most users accept. You don't need an account to edit a PDF and you can upload PDF files from your computer or from a URL. The number of PDF annotation tools is quite impressive as you can white out (hide parts of your PDF file) and insert links, insert arrows, images, sticky notes, check marks and even form fields of various types (text, checkbox, listbox, etc).
However, that's not where the features end. PDFEscape helps you delete, rotate, and move pages in your PDF file, which even in desktop PDF readers, you can usually find limited support for.
You can also encrypt the document with a password, as well as edit the details of the PDF file, such as title, author, etc. You can even save your progress as you edit while you're trying out the features (you don't have to log in), unless you browse elsewhere and lose your session. PDFEscape saves the annotation to the PDF file, unlike Okular which is a good PDF reader, but it doesn't save annotations on top of the PDF file, which makes the annotations inaccessible to other users.
Crocodoc is a polished viewer and annotator for PDF, MS Word, MS Powerpoint, PNG and JPG files. You might be reminded of Aviary's Falcon tool, which lets you annotate images (great for anyone who wants to annotate a screenshot), and web-based PDF and document viewers, like Zoho's excellent Viewer. and the Google Docs viewer, but Crocodoc also accepts other file types and has a few other features up its sleeves. Crocodoc also uses HTML5 and CSS3 instead of Flash to display documents with minimal loss of quality compared to the original files. You don't even need to create an account, as you can immediately upload a file when you arrive on the website. You get a simple viewer with zoom, text (which you can use to fill out forms), drawing tools, highlighting, and comments after your file is converted.
What makes it stand out from the other PDF annotators on this list is that it allows you to share your bookmarked PDF file with a shortened link, and even embed codes! Once you share it, you can choose to have your viewers add comments to your document. The other unique feature is that you can collaborate with others so everyone can view and annotate the file together, even if you are in remote locations. You can then see all the changes made to the document in a sidebar. Crocodoc allows you to download the original file as well as the annotated version, which you can view in Sumatra, Evince, or your favorite PDF reader, annotations and all.
Honorable mentions would go to PDFVue, (which has many of the same features PDFEscape offers in a sleek interface, but marks PDFs with a DocQ watermark) and FillAnyPDF (which is a form filler and PDF annotator, but in my tests, it appears that the annotations were not saved to the PDF file, so they were not visible when used with a desktop viewer).
What free software or web tool do you use to annotate PDF files? Share your wisdom in the comments!