Tracelytics has closed a Series A round of funding worth $5.2 million from Bain Capital Ventures with participation from existing investors Google Ventures, Battery Ventures, and Flybridge Capital Partners.

The Providence, Rhode Island-based startup makes performance and analytics tracking tools for Web applications. It soft-launched in November in tandem with a $600,000 seed round and opened its doors to customers in February. Since then, the company’s software has executed more than 500 million “traces,” or records of actions on apps.

Tracelytics tracks and analyzes performance for PHP, Python, and Ruby apps. It will expand into new languages in the next year.

The company is expanding into new cities, too: In April, Tracelytics will open a Boston office. The company plans to double its current headcount of eight by the summer, John Vigeant, CEO of Tracelytics, told me.

Tracelytics’ potential clients are anyone with traffic around a Web app, including SaaS companies, app makers, ecommerce companies, or publishers serving ads. The company’s software, unlike other performance-tracking companies, uses full stack tracing, meaning it follows more than just a fraction of an app’s performance from a handful of servers, collecting data across applications, layers, and machines.

Most legacy tracking tools break down when applied to agile, cloud-based apps, said Spiros Eliopoulos, Tracelytics’ co-founder and CTO. The idea is that, because Tracelytics tools aren’t tied to servers and are therefore more scalable, they can identify and fix problems or bugs faster. They can also understand trends and measure performance faster, he said.

It’s not terribly sexy to the less data-inclined among us, but for developers and startups trying to scale quickly, it’s exciting stuff. Aman Gupta, an engineer at Github, called his experience with the Tracelytics dashboard “mind-blowing.” Github, the social network-for-programmers, is one of Tracelytics’ first clients.

That agile scalability plays out in the company’s pricing model as well. Most of its competitors charge customers on a per-host basis, but Tracelytics charges by the number of traces the customer chooses to send to be tracked. That way customers can control costs while gaining visibility across their entire systems. “Everyone is moving toward a cloud model of usage based on pricing, but our competitors are in a legacy per-agent, per-host model,” Vigeant said. That model is not sensible in a cloud environment, he added.

Plans start at $95 a month for 300,000 traces and go up from there. For a limited time, the company is offering a free one-month trial membership on its site.