When you need to share documents with a wide audience then Adobe's PDF should probably be your format of choice: the files are small, accurate and viewable on just about any platform.

And you can easily create them on your own system with free tools like pdf995.com or doPDF.

But what if you're away from home, or need more features, like the ability to edit PDF files or create them directly from other documents?

Then it's time to start looking for free online solutions, and we've found five of the best.

1. PrimoOnline
You've created your document, but it's not in the PDF format? That's where PrimoOnline comes in. Enter your email address, point the site at your file (it can handle more than 300 common file types), and a PDF copy will be emailed to you usually within a few minutes.

PrimoOnline is very easy to use, but does limit the size of your original document to 5MB. If you breach that only occasionally then try Adobe's own Acrobat site, instead. It can work with files up to 200MB, but you only get five free conversions, so use them with care.

2. PDFVue
PDFVue is an online editor that accepts uploaded PDF files from your PC, then can manipulate them in useful ways. So you're able to rotate pages or delete them, add text, images or sticky notes, even create PDF forms. PDFVue will host the document for you, too, so you don't have to waste time manually emailing copies. Just click the Share button for a link that you can pass around.

3. PDF Hammer
If you've several PDF files that you'd like to combine then PDF Hammer could be the answer. It lets you upload multiple files, then rearrange, reorder and delete pages, and merge them into a single document. You can also add password-protection, and even update PDF metadata like the Author, Title and Subject fields. It's well presented and professional: pity about the 100 page limit on uploaded files, though.

4. PDFMaker
Don't have your original document yet? PDFMaker lets you create it directly from your browser. Just enter and format your text in the web editor, then click Download to generate a PDF copy. The site is a beta and right now you can only create simple text-based documents, but once complete you should also be able to work with images and tables, or paste in formatted documents directly from Microsoft Word.

5. HTML to PDF
PDF files are an excellent way to share the contents of a web page that's caught your eye, and there's no easier way to make this happen than HTML to PDF. There's no charge, no registration, not even any banner ads - just a lightweight page where you enter the target URL, click a button and download your PDF file.

-------------------------------------------------------------------------------------------------------

Like this article? Then check out 100 fantastic free apps for your Vista PC

Sign up for the free weekly TechRadar newsletter
Get tech news delivered straight to your inbox. Register for the free TechRadar newsletter and stay on top of the week's biggest stories and product releases. Sign up at http://www.techradar.com/register

Follow TechRadar on Twitter