Adobe invented the PDF (Portable Document Format) to solve a problem that dogged people for years: how to view and print documents without requiring the original software that document was created in or the fonts it uses. It wasn't meant to be a replacement for a word processor - it was a layout format for precise alignment of text and images.

Many programs can save documents in PDF format, and plenty can read them, web browsers included. But if you want to edit a PDF file, then you'll need an app which allows you to modify the file.

Maybe you've received a document in PDF form and need to make changes or you might only have a file in PDF format, having deleted or lost the original (editable) document. In all of these situations, you need a PDF editor.

Here's our selection of the best free ones currently available. While these give you a good amount of options in terms of editing, there are obviously some restrictions. If you want a fully-featured app and don't mind paying, then be sure to also take a look at our Best PDF editors roundup as well. 

Foxit Reader

Foxit Reader

Foxit Reader is a lightweight alternative to Adobe Reader. It's more than just a PDF reader, and has a wide range of powerful tools. You cannot edit the contents, but text can be struck through with a line and replaced by a pop-up note.

Alternatively, you can add a box over the top of text you want to replace and add new text in its place. Foxit Reader is more for annotating than rewriting, but if that's what you're after then it's an excellent free tool. 

If you require more features then you can use the online version of PhantomPDF where extra tools are available.

PDF-XChange Editor

PDF-XChange Editor

PDF-XChange Editor replaces the Viewer app, bringing with it some impressive features. It offers a similar set of tools to Foxit Reader, meaning you can create and annotate documents with ease. There's even OCR support for a few languages, including English, French, Spanish and German.

Tracker Software uses an interesting approach, in that around 60% of the features are free, but the rest require a paid license. This means you can explore it's capabilities first without having to invest any money. If you're lucky, you should be able to get all your work done for free. 

PDF Candy

PDF Candy

This online service offers various conversion options, plus the ability to split files and merge them. There are some simple editing functions available, though, including adding rectangles, highlighting zones, plus the ability to strikeout or add text. 

There's one main limitation: any file you upload must be under 50MB. But that's it: there are no ads or any other restrictions.

As long as your editing demands aren't too heavy, PDF Candy may be the quickest solution. It can also convert PDFs to other formats, rotate them, split them, protect them and add watermarks.

Apowersoft Online PDF Editor

Apowersoft Online PDF Editor

This is another excellent online service that offers a wide range of editing tools. The most notable is text editing, which is something of a rarity in the free realm, plus you can annotate documents, convert formats, and all from the comfort of a browser window.

The app does require a launcher to be downloaded before beginning, but after that it's all based online. 

AbleWord

AbleWord

AbleWord works best when importing PDFs that were created in Word, although the app will attempt to replicate all PDF files. The end result won't look identical to the original, but close enough for most people.

The interface is a bit dated now, and the app hasn't been updated for a few years, so don't expect any new features to be added or bugs to be fixed. But, if you need a free PDF editor for Word documents it's worth a look.