Oracle-backed Java and open-source Python also remain popular languages among programmers. SlashData estimates there are now 8.4 million Python developers and 8.2 million Java developers.
Others top languages with over one million users include C++, C#, Visual tools, Kotlin, Swift, Go, Ruby, Objective C. Rust is used by 600,000 developers while Lua is used by 500,000 developers.
Reflecting the importance of AI in tech today and its impact on Python usage, around three-quarters of machine-learning developers and data scientists report using Python these days, while less than 20% of these two groups use R, a popular but specialized language for statistical computing.
Kotlin has been the fastest-growing language over the past two years, gaining 1.1 million developers, probably because Google made it the preferred language for Android development. This finding lines up with GitHub's Octoverse 2018 report and 2019 report, which focus on open-source projects, though in 2019 Google's Dart was the fastest-growing language.
According to SlashData, the number of developers who report using Swift has actually declined over the past year compared with the year prior and now stands at two million. Meanwhile, Objective C is still used by 1.2 million developers, though that's also down.
The survey also found that 59% of developers contribute to open-source software. A third of developers who contribute to open-source software are under 24 years old.
Developers are also looking to open-source projects to improve their coding skills, with 29% primarily doing so for this reason compared with the 26% who do it because they believe in the benefits of open-source software. Only 3% of developers are actually getting paid for their work on open-source projects.
But developers do want corporate support, with just under half of all developers surveyed (44%) expecting companies to support and contribute to open-source communities. However, 39% of open-source developers don't expect companies to build products and services on open-source software.