Which programming languages have the largest developer communities behind them? As you might expect, ultra-popular languages such as Python and Java can boast a user base of millions—but some lesser-known languages also have surprisingly massive audiences.

SlashData’s annual State of the Developer Nation provides a handy breakdown of how many software developers actively use a particular programming language. SlashData derives these numbers from its own independent estimate of the global developer community (which it places at 31.1 million), plus a series of “large-scale, low-bias” surveys that it conducts every six months. Here are the results of that work:

JavaScript remains immensely popular. “Not only do new developers see it as an attractive entry-level language, but existing ones are also adding it to their skillset,” the report added. “Even in software sectors where JavaScript is not among developers’ top choices, like in data science or embedded development, more than a fifth of developers use it in their projects.” (And don’t forget that TypeScript, a superset of JavaScript, is also intensely popular among all kinds of developers.)

Python, Java, and other languages have likewise enjoyed steady growth. Rust is the fastest-growing language on SlashData’s list, having tripled in size over the past 24 months. “Rust has formed a very strong community of developers who care about performance, memory safety, and security,” the report added. “As a result, it is mostly used in IoT software projects but also in AR/VR development, most commonly for implementing the low-level core logic of AR/VR applications.”

SlashData’s language-ranking data aligns with that of other firms. For example, GitHub’s regular State of the Octoverse, which traces language usage on its massive platform, also shows JavaScript, Python, and Java topping other languages. With millions of developers using them, these languages will likely dominate for many years to come... but keep an eye on the smaller ones with a rapidly growing user-base.