Update: These rankings have been updated. The third quarter snapshot is available here.

With two quarters having passed since our last snapshot, it’s time to update our programming language rankings. Since Drew Conway and John Myles White originally performed this analysis late in 2010, we have been regularly comparing the relative performance of programming languages on GitHub and Stack Overflow. The idea is not to offer a statistically valid representation of current usage, but rather to correlate language discussion (Stack Overflow) and usage (GitHub) in an effort to extract insights into potential future adoption trends.

In general, the process has changed little over the years. With the exception of GitHub’s decision to no longer provide language rankings on its Explore page – they are now calculated from the GitHub archive – the rankings are performed in the same manner, meaning that we can compare rankings from run to run, and year to year, with confidence.

This is brought up because one result in particular, described below, is very unusual. But in the meantime, it’s worth noting that the steady decline in correlation between rankings on GitHub and Stack Overlow observed over the last several iterations of this exercise has been arrested, at least for one quarter. After dropping from its historical .78 – .8 correlation to .74 during the Q314 rankings, the correlation between the two properties is back up to .76. It will be interesting to observe whether this is a temporary reprieve, or if the lack of correlation itself was the anomaly.

For the time being, however, the focus will remain on the current rankings. Before we continue, please keep in mind the usual caveats.

• To be included in this analysis, a language must be observable within both GitHub and Stack Overflow.
• No claims are made here that these rankings are representative of general usage more broadly. They are nothing more or less than an examination of the correlation between two populations we believe to be predictive of future use, hence their value.
• There are many potential communities that could be surveyed for this analysis. GitHub and Stack Overflow are used here first because of their size and second because of their public exposure of the data necessary for the analysis. We encourage, however, interested parties to perform their own analyses using other sources.
• All numerical rankings should be taken with a grain of salt. We rank by numbers here strictly for the sake of interest. In general, the numerical ranking is substantially less relevant than the language’s tier or grouping. In many cases, one spot on the list is not distinguishable from the next. The separation between language tiers on the plot, however, is generally representative of substantial differences in relative popularity.
• GitHub language rankings are based on raw lines of code, which means that repositories written in a given language that include a greater number amount of code in a second language (e.g. JavaScript) will be read as the latter rather than the former.
• In addition, the further down the rankings one goes, the less data available to rank languages by. Beyond the top tiers of languages, depending on the snapshot, the amount of data to assess is minute, and the actual placement of languages becomes less reliable the further down the list one proceeds.

(click to embiggen the chart)

Besides the above plot, which can be difficult to parse even at full size, we offer the following numerical rankings. As will be observed, this run produced several ties which are reflected below (they are listed out here alphabetically rather than consolidated as ties because the latter approach led to misunderstandings).

1 JavaScript
2 Java
3 PHP
4 Python
5 C#
5 C++
5 Ruby
8 CSS
9 C
10 Objective-C
11 Perl
11 Shell
13 R
14 Scala
15 Haskell
16 Matlab
17 Go
17 Visual Basic
19 Clojure
19 Groovy

By the narrowest of margins, JavaScript edged Java for the top spot in the rankings, but as always, the difference between the two is so marginal as to be insignificant. The most important takeaway is that the language frequently written off for dead and the language sometimes touted as the future have shown sustained growth and traction and remain, according to this measure, the most popular offerings.

Outside of that change, the Top 10 was effectively static. C++ and Ruby jumped each one spot to split fifth place with C#, but that minimal distinction reflects the lack of movement of the rest of the “Tier 1,” or top grouping of languages. PHP has not shown the ability to unseat either Java or JavaScript, but it has remained unassailable for its part in the third position. After a brief drop in Q1 of 2014, Python has been stable in the fourth spot, and the rest of the Top 10 looks much as it has for several quarters.

Further down in the rankings, however, there are several trends worth noting – one in particular.

• R: Advocates of the language have been pleased by four consecutive gains in these rankings, but this quarter’s snapshot showed R instead holding steady at 13. This was predictable, however, given that the languages remaining ahead of it – from Java and JavaScript at the top of the rankings to Shell and Perl just ahead – are more general purpose and thus likely to be more widely used. Even if R’s grow does stall at 13, however, it will remain the most popular statistical language by this measure, and this in spite of substantial competition from general purpose alternatives like Python.

• Go: In our last rankings, it was predicted based on its trajectory that Go would become a Top 20 language within six to twelve months. Six months following that, Go can consider that mission accomplished. In this iteration of the rankings, Go leapfrogs Visual Basic, Clojure and Groovy – and displaces Coffeescript entirely – to take number 17 on the list. Again, we caution against placing too much weight on the actual numerical position, because the differences between one spot and another can be slight, but there’s no arguing with the trendline behind Go. While the language has its critics, its growth prospects appear secure. And should the Android support in 1.4 mature, Go’s path to becoming a Top 10 if not Top 5 language would be clear.

• Julia/Rust: Long two of the notable languages to watch, Julia and Rust’s growth has typically been in lockstep, though not for any particular functional reason. This time around, however, Rust outpaced Julia, jumping eight spots to 50 against Julia’s more steady progression from 57 to 56. It’s not clear what’s responsible for the differential growth, or more specifically if it’s problems with Julia, progress from Rust (with a DTrace probe, even), or both. But while both remain languages of interest, this ranking suggests that Rust might be poised to outpace its counterpart.

• Coffeescript: As mentioned above, Coffeescript dropped out of the Top 20 languages for the first time in almost two years, and may have peaked. From its high ranking of 17 in Q3 of 2013, in the three runs since, it has clocked in at 18, 18 and now 21. The “little language that compiles into JavaScript” positioned itself as a compromise between JavaScript’s ubiquity and syntactical eccentricities, but support for it appears to be slowly eroding. How it performs in the third quarter rankings should provide more insight into whether this is a temporary dip or more permanent decline.

• Swift: Last, there is the curious case of Swift. During our last rankings, Swift was listed as the language to watch – an obvious choice given its status as the Apple-anointed successor to the #10 language on our list, Objective-C. Being officially sanctioned as the future standard for iOS applications everywhere was obviously going to lead to growth. As was said during the Q3 rankings which marked its debut, “Swift is a language that is going to be a lot more popular, and very soon.” Even so, the growth that Swift experienced is essentially unprecedented in the history of these rankings. When we see dramatic growth from a language it typically has jumped somewhere between 5 and 10 spots, and the closer the language gets to the Top 20 or within it, the more difficult growth is to come by. And yet Swift has gone from our 68th ranked language during Q3 to number 22 this quarter, a jump of 46 spots. From its position far down on the board, Swift now finds itself one spot behind Coffeescript and just ahead of Lua. As the plot suggests, Swift’s growth is more obvious on StackOverflow than GitHub, where the most active Swift repositories are either educational or infrastructure in nature, but even so the growth has been remarkable. Given this dramatic ascension, it seems reasonable to expect that the Q3 rankings this year will see Swift as a Top 20 language.

The Net

Swift’s meteoric growth notwithstanding, the high level takeaway from these rankings is stability. The inertia of the Top 10 remains substantial, and what change there is in the back half of the Top 20 or just outside of it – from Go to Swift – is both predictable and expected. The picture these rankings paint is of an environment thoroughly driven by developers; rather than seeing a heavy concentration around one or two languages as has been an aspiration in the past, we’re seeing a heavy distribution amongst a larger number of top tier languages followed by a long tail of more specialized usage. With the exceptions mentioned above, then, there is little reason to expect dramatic change moving forward.

Update: The above language plot chart was based on an incorrect Stack Overflow tag for Common Lisp and thereby failed to incorporate existing activity on that site. This has been corrected.