Railo is described as 'Open Source ColdFusion Markup Language (CFML) server and the fastest CFML engine available. We offer expert CFML consulting services from world class ColdFusion experts'. There are four alternatives to Railo for Windows, Linux and Mac. The best alternative is Adobe ColdFusion. It's not free, so if you're looking for a free alternative, you could try Lucee or BlueDragon.