The headline of the March 2025 edition of the TIOBE index had and its headline "The dinosaurs strike back" referring to the fact that Ada was the month's new entry to the Top 20 and the notable resurgence in popularity of Delphi which had snuck back into the Top 10, displacing Fortran.

As I-Programmer readers already know, we regularly cover the TIOBE Programming Community Index index to see the ups and downs of program language popularity. In case you are not familiar with it, this index is intended to serve an indicator of the popularity of programming languages based on the number of skilled engineers world-wide, courses and third party vendors. Data from Google, Amazon, Wikipedia, Bing and more than 20 other websites are used to calculate the ratings, essentially a percentage share of all mentions.

The TIOBE index does however need to be regarded with some healthy scepticism. Its own rubric states: 

It is important to note that the TIOBE index is not about the best programming language or the language in which most lines of code have been written.

It's usefulness is intended to be in does reflect variations in the demand for skills in different programming languages but it has a tendency to an overshoot/undershoot pattern which gives its Top 10 Chart its characteristic zig-zag pattern. 

The TIOBE Index of March 2025

The chart for March 2025 shows no change from the previous edition in the rankings of the languages at the top at the chart, but notice the enormous gap between Python, which has now has a rating of 23.85%, and the three closest rivals, C++, Java and C, clustered around 10%. It was this trio of languages that were the top three (in the reverse order and quite widely spaced apart) in June 2001, the earliest date in the Top 10 Chart. At that time Python ranked #9 with a rating of 1.25% while Java which was top had its highest ever rating of 24.69%.

Dinosaurs Revitalized

Paul Jansen, CEO of TIOBE Software, who maintains the index provides an insightful report each month. In March 2025 he noted:

It is interesting to see that very old languages are sneaking into the TIOBE index top 20. Fortran and Delphi are competing for a top 10 position, whereas COBOL and this month's new entry Ada are a little bit further down the list. All of them show an uptrend. Why is this? Why aren't the new and promising languages shining instead?

Jansen comes up with a very plausible explanation for why there has been a resurgence in interest in these particulars languages - the need to maintain legacy software at a time when the programmers who originally developed the systems have either already retired or are on the point of retiring. While the headline refers to the languages as "dinosaurs" Jansen also points out that they have evolved over time and have new language definitions, listing Fortran 2023, Delphi 12 (released in 2024), Ada 2023 and COBOL 2023. 

Legacy Languages Linger

Prompted by the TIOBE index, I've contemplated the performance of "legacy languages"  previously, see for example Delphi About To Fall Out Of TIOBE Index Top 20 back in 2020.  At that time I commented on other "legacy" languages, revealing that COBOL was at #26 with a rating of 0.48%, Lisp at #29 with a rating of 0.37%, FORTRAN  at #33 with a rating of 0.29% and Ada at #37 with a rating of 0.23%. Delphi was at #20 with a rating of 0.71%

Looking at any TIOBE Top 10 Chart, there is a very apparent downward trend. The explanation for this is that over time new languages emerge and become popular and get added to the TIOBE Index which currently tracks a total of 100 programming languages. While these new languages might be expected to displace old languages that would fall of the radar this isn't the case in practice. Languages such as Cobol and Fortran are deeply embedded in universities and enterprise and cannot possibly be allowed to disappear. As Mike James previously expressed the situation:

"Old languages never die they simply become less loved."

Comparing Ranking

There are alternative ways to rank programming languages which result in different languages coming top. IEEE Spectrum's annual Top Programming Languages exercise provides evidence of this by providing three alternative "meta rankings" - Jobs and Trends in addition to its baseline Spectrum ranking, based on data from multiple sources with different weights applied. This ranking was started in 2014 and in 2024, its 11th year, Python has come top in the Spectrum ranking in nine consecutive years.

A different approach is that of Red Monk, a twice-yearly exercise that uses data from GitHub and Stack Overflow with the aim of producing a popularity ranking that reflects both volume of code and of discussion. See Why Do Some Languages Always Come Top? for an explanation of why JavaScript has held its position at the top of this ranking since it was devised in 2010.  One that was new to us only last year is Programming Language Database, PLDB. Active since 2017 it is maintained by Breck Yunits, This database has information on over 5,000 programming languages and keeps a list of the Top 1K languages, ranking them by combining scores for:

• number of estimated users
• number of estimated jobs
• number of languages a language has influenced
• number of measurements PLDB has on a language
• number of languages built using this language 

Currently JavaScript occupies #1 in this ranking, with C at #2 and Python #3.