Blackfire.io is described as 'Blackfire is a performance management solution' and is an app in the OS & Utilities category. There are three alternatives to Blackfire.io for a variety of platforms, including Linux, Online / Web-based, Android, iPhone and Chrome OS. The best alternative is New Relic, which is free. Other great apps like Blackfire.io are SPX (Free, Open Source) and Dynatrace (Paid).
Pinpoint and solve performance issues in your Ruby, Java, .NET, PHP and Python apps with real user, application and server monitoring. Free accounts can ping a website every 1 minute, from multiple locations around the globe, and send email alerts.
SPX, which stands for Simple Profiling eXtension, is just another profiling extension for PHP. It differentiates itself from other similar extensions as being: totally free and confined to your infrastructure (i.e. no data leaks to a SaaS).