Adobe's Portable Document Format has become the standard format for distributing digitized documents. But how can you proceed when you need to fill out a form, add your signature to a document, or correct an error--and the PDF file is locked to editing? Blueberry's free PDF Form Filler is the answer.

With PDF Form Filler, you can place text anywhere on any PDF, check boxes, insert notes or images, and even add drawings. Plus, you can introduce items even when the PDF has been password-protected to prevent editing. It's very basic: Almost the same as printing out the PDF and taking a pen to paper, only it's more efficient, conserves your ink, and lets you save your amended file as a PDF.

One of the few annoying features of Blueberry's PDF Form Filler is that it remains on the tool you select until you choose the pointer. For example, to use PDF Form Filler to add an image to your PDF file, you must select the insert image tool and then click anywhere in the file; but then you have to remember to select the pointer; otherwise, you'll keep adding images.

PDF Form Filler has a few quirks, too, especially when you use it to open a password-protected PDF: Sometimes you just can't do it, even if you have the correct password. Also, if the original PDF's file permissions don't allow editing, your saved PDF Form Filler version won't allow you to edit your own changes or additions either; if you make a mistake, you'll have to go back to the original and make your changes again.

Peculiarities aside, PDF Form Filler is one of the most precise PDF editors I've used, possibly because the program ignores much of the information embedded in the PDF. Some of the best free PDF readers, including Foxit Reader, Nitro PDF Reader, and PDF Xchange Viewer, try to interpret the PDF. For example, in an attempt to help you fill out forms they'll identify form fields. PDF Form Filler doesn't do that, and in some instances its simplicity makes PDF Form Filler less frustrating to use.

Few computers lack a copy of Adobe Reader, or some similar product. Some Reader competitors include advanced features for searching, editing, stamping, and amending your PDFs. However, Blueberry PDF Form Filler is the best way to get around Adobe's file permissions: If you can open the PDF, you can add to it and save the file with PDF Form Filler. For occasions when that's all you need, Blueberry PDF Form Filler is a great tool to have.

--Clare Brandt