Developer Migration Patterns Between Programming Languages
Key findings from the 2025 State of Developer Ecosystem survey on language switching trends
1Core motivations behind language migration
According to JetBrains' 2025 Developer Ecosystem survey, project requirements remain the primary reason for switching languages. Kotlin stands out as an exception - developers migrate to it for its superior developer experience and modern features. C shows surprisingly high churn rates, while Java developers predominantly move to Python and TypeScript.
2Mobility in HTML/CSS and JavaScript
HTML/CSS developers learn JavaScript to enhance job opportunities, while JavaScript developers migrate to nearly all other languages for the same reason. Despite being the most widely used language, JavaScript is the main language for only 6% of software developers. Java maintains significantly higher popularity as a primary language.
3Historical perspective on language evolution
Programming history is partly a history of escapes - from assembly to C, from C to managed runtimes, from Java to Kotlin, from dynamic languages to TypeScript. Each new language emerged to address specific limitations in certain contexts. Technological advancements like the rise of IoT have significantly influenced these transitions.
4Challenges in measuring language migration
JetBrains discovered that developers' plans to switch languages often don't materialize. While many plan to try Rust or switch from Java to Kotlin, far fewer actually make the transition. This led the company to introduce new questions about developers' primary languages from 12 months prior, providing more accurate migration data.
5Rising languages of 2025
TypeScript and Rust emerge as the fastest-growing languages in 2025. While growth was predicted for Python, Go, and Lua, only Go met expectations. JetBrains' Language Promise Index indicates TypeScript, Rust, Python, and Go still have substantial growth potential, whereas Lua appears to have hit a growth ceiling.
6Primary language usage statistics
Based on 8,837 responses, increases in Java and Kotlin shares likely reflect sample changes rather than actual trends. Although JavaScript is the most popular language overall, only 6% of developers use it as their primary language. Java remains significantly more prevalent as a main language among professional developers.
7Language loyalty and churn rates
The survey measures developer loyalty and abandonment rates across languages. Loyals (those who stick with a language) and churners together account for 100%. Net growth calculations incorporate newcomers and other factors, providing valuable insights into languages' long-term sustainability.
8Kotlin's unique position
Kotlin stands out as the only language developers adopt by choice rather than necessity. Its superior developer experience and modern features attract a significant portion of Java developers. JetBrains data shows Java-to-Kotlin migration ranks as the third most common language switch by absolute numbers.
9TypeScript's ascent
Many developers are switching their primary language from JavaScript to TypeScript while continuing to use JavaScript as a secondary language. TypeScript's static typing and better IDE support make it particularly attractive for large-scale projects. JetBrains notes TypeScript still has considerable growth potential.
10Rust's impact on systems programming
Rust is gaining rapid popularity for safe systems programming needs. Its combination of memory safety and performance particularly appeals to C/C++ developers. Survey data indicates Rust is among the fastest-growing languages, with this trend expected to continue.
11Python's versatility
Python maintains dominance in diverse fields like data science, machine learning, and web development. Java developers migrating to Python reflects the language's versatility and extensive library ecosystem. However, 2025 data suggests Python's growth is slowing in some areas.
12The importance of developer experience
Survey findings highlight developer experience as a critical factor in modern programming languages' success. Languages like Kotlin and TypeScript stand out with features that enhance developer productivity. JetBrains predicts this factor will become increasingly important in future language design.
Original article: The JetBrains Blog — Geliştiricilerin Programlama Dilleri Arasındaki Göç Haritası