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 made changes or corrections. You' 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.

However, here's the thing: free editors generally do not allow you to edit text. What they usually offer is the ability to erase (or 'whiteout') text and replace it with new text. Matching the font, both size and colour, might be possible, but it's not the same as actually editing the original text.

Some free PDF editors let you annotate PDFs and add or remove pages. The original content cannot be changed, but you can insert notes and comments, use a highlighter pen, strikethrough text, delete pages, fill out forms and so on.

Others, such as Google Docs, allow you to open a PDF from Google Drive but essentially copy the text only and ditch the images, links and formatting. Useful if you just want the text, but not that great if you wanted to tweak a few things without ruining the look.

Fortunately, there are a few editors which should have the editing options you need. So, if you want a free way to edit PDF files, here are the apps we recommend trying out. In some cases you can upgrade to the paid-for or 'Pro' version to get more tools, but if you're in a hurry and none of these free options do what you need, then check out our roundup of the best PDF editors - paid-for apps which do everything. If you have no time to read that, then simply buy Nuance Power PDF 3

AbleWord

AbleWord

AbleWord is the only free PDF editor we're aware of that can import a PDF and make it completely editable. It's best when importing PDF files that were created in Word, but will attempt to replicate all PDF files. The end result won't look identical to the original but will be close.

Foxit Reader

Foxit Reader

Foxit Reader is a lightweight alternative to Adobe Reader and many people prefer it. 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 text box over the top of text you want to replace and use the 'typewriter' tool to add new text in its place.

For many people, Foxit Reader will include most of the editing tools required, but if it doesn't you can click 'Edit PDF' under Extras in the top menu to be taken to the online version of PhantomPDF where more editing tools are available.

PDF-Xchange Viewer

PDF-Xchange Viewer

PDF-XChange Viewer offers an almost identical set of features to Foxit Reader and it is useful for annotating in a similar manner with mark-up and highlighting.

There's even OCR support for a few languages in the free version, including English, French, Spanish and German.

PDF Candy

PDF Candy

This online service isn't so much an editor, but it may offer the conversion options you need, including 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 text and add text. 

There's one main limitation: any file you upload must be under 10MB. 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.

Don't bother downloading the Windows app: it essentially replicates the online functions but only allows you to perform two tasks before demanding that you pay for the 'Pro' version.

LibreOffice 6

LibreOffice 6

LibreOffice, the free Office alternative, is worth considering if you want to edit the text in a PDF file. It loads PDFs and it can cope with very large documents with hundreds of pages. The only snag is that each line of text is text box, which makes it awkward to edit large amounts of text.

FormSwift PDF Editor

FormSwift PDF Editor

FormSwift is another online PDF editor. You simply drag and drop files to upload them, and you can then edit them in your browser before downloading and printing or sharing.

You can edit text by deleting and replacing it, add images or signatures. It's relatively basic, but it's free and requires only an internet connection.

PDF to Word

PDF to Word

PDF to Word does exactly what the name says. You select a file on your PC, upload it to the site and it emails you the Word document a minute or two later. The advantage of this is that you can use Word or another word processor to edit the text and resave the document as a PDF.