Linux, Mac OS X, BSD, Windows (Cygwin)
Use of the API requires authentication with your API key. Your key is displayed in the right column in your dashboard. If you do not yet have an account, please register for a free account.
Browshot's simple API makes it very easy to request screenshot and retrieve a thumbnail in a single URL.
You can use your OS favorite command line tool to download a page with Browshot: wget, curl, fetch, etc.
Take a look at the simple API section to understand how to generate the URL.
If you need more granular control over the screenshots, you can use the free libraries for Perl, Python and Ruby.