New Relic started out focusing on helping developers gauge how their Web sites and services were performing. And the company’s tools are still used to develop and improve products, from determining why a site is slow to finding JavaScript errors or pinpointing which browsers are the most troublesome. Today, the company monitors 4 million applications and as many as 690 billion data points every day. And it offers a complete set of tools that work with virtually every popular platform, from Amazon Web Services and Microsoft Azure to Android and iOS.