The PDF file format was originally created by Adobe in the early '90s and there are now over 700+ million PDF documents on the Internet according to Google (search for filetype : pdf).
There are several reasons why the PDF file format is so popular for exchanging all sorts of documents including presentations, CAD Drawings, invoices and even legal forms.
1. PDF files are generally more compact (smaller in size) than the source document and they preserve the original formatting.
2. Unlike Word and other popular document formats, the content of a PDF file cannot be modified easily. You can also prevent other users from printing or copying text from PDF documents.
3. You can open a PDF file on any computer or mobile device with free software like Adobe Acrobat Reader. Google Chrome can read PDFs without requiring plugins and it can create PDFs.
Edit PDF Files using Free Alternatives to Adobe Acrobat
While PDF Files are "read only" by default, there are ways by which you can edit certain elements* of a PDF document for free without requiring the source files or any of the commercial PDF editing tools like Adobe Acrobat.
We will primarily focus on tools that let you alter the actual contents of a PDF file>. If you are looking to manipulate the PDF file structure itself like rearranging pages or merging multiple PDFs into one, please refer to this detailed Adobe PDF Guide.
An Online PDF Editor for Basic Tasks
Sometimes you need to make minor changes to a PDF file. For instance, you may want to hide your personal phone number from a PDF file before uploading it online or may want to annotate a page with notes and freehand drawings.
You can perform such edits in a PDF easily with PDFEscape.com, an online PDF editor that is free and also lets you edit password-protected PDF documents in the browser.
With PDF Escape, you can hide parts of a PDF file using the whiteout tool or add annotations with the help of custom shapes, arrows, text boxes and sticky notes. You can add hyperlinks to other PDF pages / web documents.
Hiding is different from redaction because here we aren't changing the associated metadata of a PDF file but just hiding certain visible parts of a PDF file by pasting an opaque rectangle over that region so that the stuff beneath the rectangle stays invisible.
Change Metadata of PDF Files
If you would like to edit the meta-data associated* with a PDF document, check out Becy PDFMetaEdit. This is a free utility that can help you edit properties of a PDF document including the title, author name, creation data, keywords, etc.
The tool can also be used for removing PDF passwords as well as for encrypting PDF documents such that only users who know the password can read the contents of your PDF files. And since this PDF metadata plus bookmarks editor can be executed from the command line, you can use it to update information in multiple PDF files in a batch.
If you planning to post your PDF files on the web, you should consider adding proper metadata to all the files as that will help improve the organic rankings of your PDF files in Google search results.
Edit the Text of a PDF File
If you want to edit the text in a PDF file but don't have access to the source documents, your best bet is that you convert the PDF file into an editable Word document or an Excel spreadsheet depending on the contents of the PDF.
Then edit these converted PDFs in Microsoft Office (or Google Docs) and export the modified files back into PDF format using any PDF writer.
If your PDF document is mostly text, you may use the desktop version of Stanza to convert that PDF into a Word document. If the document includes images, charts, tables and other complex formatting, try the online PDF to Word converter from BCL Research or the one from NitroPDF – the former offers instant conversion while the latter service can take up to a day though its yields more accurate results.
Advanced PDF Editing (Images, text, etc.)
Now that you know the basic PDF editing tools, let's look at another set of PDF editors that are also free but can help you do some more advanced editing like replacing images on a PDF file, adding signatures, removing blocks of text without breaking the flow of the document, etc.
First there's PDF XChange, a free PDF viewer and editor that you also may use for typing text directly on any PDF page. PDF XChange also supports image stamps so you may use the tool for signing PDF files or for inserting images anywhere on a PDF page.
Then you have Inkscape, a free vector drawing tool (like Adobe Illustrator) that can natively import and export PDF content.
