Here’s a sure indication that Node.js is getting big: more employers are marking the server-side framework with JavaScript as a required job skill.

See also: How Node.js Stays On Track

As InfoWorld‘s Serdar Yegulalp notes, job openings on Indeed.com that require Node.js skills have jumped from zero to 4,000 since 2011. Ranging from Node.js-specific positions to general programming jobs that require the knowledge along with several other frameworks, Node jobs around the country offer salaries ranging from $60K to mid-100Ks.

While there are still fewer listings for Node.js skills than there are for Python (31,000) or Ruby (18,000), those numbers have peaked in the same time period. Judging by the graph, Ruby may even be past its height. Yet, Node.js jobs continue to grow.

The fact that demand for Node.js jobs has grown so starkly since 2011 indicates the framework’s potential to remake the programming landscape. As need for their talent grows, Node.js developers could be some of the most highly sought after in the future.

The Rise Of Node.js = The Rise Of Mobile

An increasingly mobile Web has paralleled the rise of Node.js. Mobile devices make up at least 30% of total Web traffic, and Node.js is a framework with a lot to offer mobile app developers.

See also: What You Need To Know About Node.js

Mobile apps are designed to serve Web pages to mobile users. Most of the heavy lifting goes on in the back end of a mobile app, where websites are made available and managed. That means back-end frameworks, like lightweight Node.js, are enjoying a moment in the spotlight.

Node.js makes a great back-end framework for mobile development because its core purpose is to respond to network requests. The way this works on mobile is that iOS, Android and other mobile web clients connect to NodeJS over HTTP to send requests through an API.

Since Node.js is an asynchronous framework, it is able to handle multiple HTTP requests in tandem, and therefore handle more traffic than many competing back-end frameworks. Combine it with Node.js’s ease of development (since it uses popular language JavaScript), and you’ve got the technical explanation for why developers refer to Node.js as fast or “responsive.”

Larger technology companies have already noticed the appeal. In 2011, LinkedIn swapped Ruby on Rails for an overhauled mobile app running Node.js. Since then, the Node.js GitHub page has recorded hundreds of companies, including eBay and Walmart, that are implementing Node.js for increasingly mobile purposes.

The spike in job listings is an indication that still more companies are hoping to adopt Node.js into their mobile plans. Developers, it’s time to list “Node.js” higher up on your resumes.