Research report·
Sizing programming language communities
JavaScript is the largest programming language community, with approximately 27M developers worldwide as of Q3 2025.
The 30th edition of SlashData's State of the Developer Nation series sizes the leading programming language communities as of Q3 2025. It estimates the number of developers using each language, identifies which languages are growing fastest, and ranks them against one another across five survey waves from Q3 2023 to Q3 2025. The report is grounded in SlashData's independent estimate of just over 48M active software developers worldwide, combined with large-scale surveys asking developers about their language use across 13 areas of development. Beyond raw population sizes, it examines how language choices shift as developers move through their careers — distinguishing early-career, mid-career and experienced cohorts. Findings cover JavaScript's maturity and flattening trajectory, Python overtaking Java for second place, the resurgence of C/C++ in performance-critical work, and Ruby's steady comeback. It is written for product executives and tool vendors weighing which languages, SDKs and platform features to prioritise.
/Key findings
- JavaScript is the largest language community at approximately 27M developers (26.9M), though its usage dipped from 61% in Q3 2024 to 56% in Q3 2025.
- Python (24M) has overtaken Java (23M) as the second-largest language community over the past six months.
- The combined C/C++ user base increased by 8.7M active developers over two years; C++ alone grew by 7.6M, rising from 33% to 47% in embedded projects.
- Ruby (4.9M) has doubled its population over two years, adding 2.8M developers, from 5% in Q3 2023 to 10% in Q3 2025.
- PHP and C# skew towards more experienced developers; C# rises from 18% among newcomers to 30% among the most experienced, while JavaScript stays high across all experience levels (52% to 57%).
/Questions this report answers
Which programming language has the most developers in 2025?
JavaScript is the largest language community, with approximately 27M active developers worldwide (26.9M) as of Q3 2025.
Has Python overtaken Java in popularity?
Yes. Over the past six months Python (24M) surpassed Java (23M) to become the second-largest language community, achieved through small gains across multiple contexts.
How many software developers are there worldwide?
SlashData estimates there are just over 48M active software developers worldwide as of Q3 2025.
Which language is growing fastest?
C++ is the momentum story, adding 7.6M active developers over two years, with use in embedded software rising from 33% in Q3 2023 to 47% in Q3 2025, and in machine learning from 19% to 26%. Ruby doubled its base, adding 2.8M developers.
Do programming language preferences change with developer experience?
Yes. Python appeals more to early- and mid-career developers (52%, dropping to 45% among the most experienced), while PHP and C# skew senior. JavaScript remains prominent across all experience levels, and adoption generally peaks among mid-career (3–10 years) developers.
Why do PHP and C# attract more experienced developers?
Both are most often encountered within established organisations and legacy systems — PHP underpins platforms such as WordPress (over 40% of all websites) and C# sits at the heart of Microsoft's .NET — so developers tend to adopt them on the job rather than as a first language.
/Who it's for
- Product executives deciding which languages, SDKs and APIs to prioritise
- Tool and platform vendors aligning strategy with developer demand
- Developer relations and marketing leads targeting specific developer cohorts