Measuring programming language popularity

TIOBE Programming Community Index based on number of skilled engineers world-wide, courses and third-party vendors 

Python, C++, C, Java, C#, JavaScript, Go, SQL, Visual Basic, Fortran, Delphi, Swift, Assembly, Matlab, PHP, Scratch, Rust, Kotlin, COBOL 

IEEE Spectrum Top Programming Languages 

Python, Java, JavaScript, C++, TypeScript, SQL, C#, Go, C, HTML, Rust, Mathematica, PHP, Shell, Lua, SAS, Kotlin, Ruby, Dart, R 

RedMonk Programming Language Rankings Top Rank on Stack Overflow by # of Tags and GitHub by # of Projects 

JavaScript, Python, Java, PHP, C#, TypeScript, CSS, C++, Ruby, C, Swift, Go, R, Shell, Objective-C, Scala, Kotlin, PowerShell, Rust, Dart 

Stack Overflow developer survey JavaScript/Rust 

ZDNET Index of Programming Language Popularity Python, JavaScript, Java, C++, C#, C, Typescript, SQL, HTML/CSS, PHP, Shell, Go, Rust

New Languages: Apple Swift, Google Go, Mozilla Rust, Gnome Vala 

PyPL PopularitY of Programming Language tutorial

Hub Reports: GitHub Languages

Trendy Skills category, salary, ranking, ads

The Transparent Language Popularity Index at SourceForge search engine

Language Breakdown in Open Source OOS open-source software

State of the Computer Book Market 2008, part 4 -- The Languages

State of the Computer Book Market - Mid-Year 2009

Programming language popularity by the number of postings in Usenet newsgroups