The vast majority of these services are remotely hosted. This means that you simply have to add a few lines of HTML code to your pages. A small number of these services are CGI scripts which must be loaded on your server.
Many of these services are free. Some require a banner ad (usually on a results page) or a link back to their page. A few require a small one-time or recurring fee.
Most of these services require that you register with the provider, but this is usually free.
Please be sure to read the "fine print" regarding these services before using them.
We are not responsible for your use of these services.