How to use web-fonts legally? [closed]
Be careful with "free" fonts on the web. Many are just copies of protected fonts with their copyright notices removed.
If you want to make sure, buy a font from one of the large foundries like fonts.com or myfonts.com. Make sure you read their license. For example, if you buy a font, you are almost always free to use it in print products, on graphics on your web site, etc., but you are almost never allowed to re-distribute a digital version of the font, not even to display it on your web site using Tools like sIFR. If you want to make sure, and big things are at stake, make sure and contact the font vendor first.
There are genuine free fonts (they also come with a license but should be much more permissive than commercial fonts). Check out Ray Larabie's works for example, the Open Font library or the League of Movable Type.
You can use all fonts of Google Font API.
From the FAQ:
Can I use the Font API on any page?
Yes. All the fonts in the Google Font Directory are licensed under open source licenses that let you use them on any website, from a private blog to a big commercial site.
There are several issues here. Also, from your post it's not clear whether you intend to just reference the fonts in your app, package them with your app or display text in images that were produced with the fonts.
It is legal to use a font that's already installed on the user's system. That's why there's no issue with Arial, Times, etc. You are not redistributing them with your app.
When you redistribute a font with your app then you have to worry about licensing. Read the license carefully.
There are free fonts. These are available in various places under various free licenses. A little Googling turns up various pages with promising-looking free fonts.
You might look at the free fonts distributed with XFree86. They aren't as high-quality as the commercial fonts, though.
That depends on how you use the font.
If you specify a font name in CSS, you can specify any font you like:
style="font-family:Some Commercial Font That You Do Not Own, Arial, sans-serif;"
If the visitor owns the font and has it installed, it will be used, otherwise the next fallback font (in this case Arial) will be used instead. As it's the visitor that has to own the font to see it displayed, you don't have to own the font just to put it's name in the code.
If you offer the font as download, naturally you need the permission of the creator unless the font is free distribute. If you embed the font you need to own it, but as it's not a download you don't need special permission to display it.
If you use the font in images that you display on your page, you need to own the font to create the images, but normally the images are then owned by you.
You might be interested in new services such as fontsquirrel or typekit that allow you to pay a recurring fee in exchange for access to a database of commercial fonts that are fully licensed and legal.
http://www.fontsquirrel.com/
http://typekit.com/