What code is Google written in?

Google’s vast array of products, services, and infrastructure is written in a variety of programming languages, depending on the specific use case, performance requirements, and the team responsible for building that particular system. Here's a breakdown of the most prominent programming languages used at Google:

1. C++

• Use Cases:
  • Core Infrastructure: Google’s foundational infrastructure, including servers, networking components, and backend systems, often rely on C++ due to its performance and low-level system access.
  • Google Chrome: One of Google’s flagship products, the Chrome web browser, is largely written in C++ to maximize speed and efficiency.
  • Performance-Critical Applications: Many of Google’s large-scale distributed systems and performance-sensitive applications use C++ for its efficiency in managing memory and handling concurrency.

2. Python

• Use Cases:
  • Automation and Scripting: Python is frequently used for scripting, automation, and tooling within Google. It’s a preferred language for quickly prototyping and developing internal tools.
  • Machine Learning and AI: Python is the primary language used in many machine learning and AI projects at Google, including TensorFlow, a popular open-source machine learning library developed by Google. While TensorFlow has C++ underpinnings, Python is used extensively for building models and interacting with the library.
  • Data Analysis and Backend Services: Python is used for data analysis, data pipelines, and in some backend services where rapid development and readability are prioritized over raw performance.

3. Java

• Use Cases:
  • Android Development: Java is a core language for Android app development. Since Google owns Android, Java has historically been one of the primary languages used to build and maintain the Android ecosystem.
  • Google Cloud: Java is used in Google Cloud services and infrastructure, as well as in APIs and large-scale enterprise applications that require robust, scalable solutions.
  • Big Data and Backend Services: Java is used for backend services, particularly in systems that require scalability, security, and performance.

4. Go (Golang)

• Use Cases:
  • Cloud Infrastructure and Services: Go was created at Google to solve issues with system software scalability and performance. It is now widely used in building Google’s cloud services and infrastructure, particularly within Google Cloud and Kubernetes, which is an open-source container orchestration platform originally developed by Google.
  • Microservices and Distributed Systems: Go is commonly used for developing microservices due to its simplicity, concurrency features, and performance.

5. JavaScript (and TypeScript)

• Use Cases:
  • Front-End Development: Google uses JavaScript heavily for front-end development, particularly in web-based applications like Google Docs, Google Drive, and Gmail.
  • Angular Framework: Google developed Angular, a popular JavaScript framework for building web applications. Angular and JavaScript are central to many of Google’s web-based products.
  • TypeScript: TypeScript, a superset of JavaScript developed by Microsoft, is also widely used within Google for front-end development due to its strong typing, which improves maintainability and reduces bugs in large-scale projects.

6. Java (for Android) & Kotlin

• Use Cases:
  • Android Development: While Java has been the traditional language for Android development, Google has embraced Kotlin, which has become the preferred language for Android app development due to its modern features, safety, and conciseness.
  • New Android Apps: Most modern Android apps built by Google, as well as many external developers, are written in Kotlin, though Java is still widely used.

7. Dart (and Flutter)

• Use Cases:
  • Cross-Platform Mobile Development: Dart is the language used in Flutter, Google’s UI toolkit for building cross-platform applications (iOS, Android, web, desktop) from a single codebase. Flutter and Dart have gained popularity both within Google and across the industry for mobile and web development.

8. Other Languages

• C: While C++ is more commonly used, C is still used in some low-level system components, especially when direct interaction with hardware or operating system components is needed.
• Objective-C and Swift: These languages are used for iOS development, although they are less prominent at Google than Kotlin and Java, which are used for Android development.
• PHP: Although not as widely used as other languages, PHP is employed in some Google tools and services. For example, YouTube’s backend originally had PHP components before being refactored.

9. SQL and Other Query Languages

• Use Cases:
  • Data Management: Google uses SQL and variations of SQL (such as BigQuery’s SQL-like syntax) for managing and querying data in databases, data warehouses, and data analytics platforms.
  • Big Data Processing: SQL is commonly used alongside other big data tools and technologies in Google’s data analytics systems.

10. TensorFlow and Other AI Tools

• Primary Language:
  • Python and C++: TensorFlow, one of Google’s most famous open-source projects for machine learning and AI, has its core components written in C++ for performance. However, the primary interface for developers and researchers is Python, which makes it easier to build models and work with the library.

Why Does Google Use Multiple Languages?

a. Right Tool for the Job

Google adopts a polyglot approach to programming, meaning they use different languages for different tasks based on their strengths. Each programming language has its unique features that make it suitable for specific use cases:

• C++ for performance-critical systems.
• Python for rapid development and data analysis.
• Java for large-scale enterprise applications.
• Go for modern cloud infrastructure.

b. Diverse Product Portfolio

Google’s wide range of products and services—spanning web applications, mobile apps, cloud computing, AI research, and backend systems—necessitates the use of multiple programming languages to meet the specific demands of each domain.

c. Legacy Systems and New Technologies

As Google has grown over the decades, many of its original systems (written in C++, Java, etc.) continue to function alongside newer technologies (like Go, Kotlin, and Dart). Google maintains a balance between maintaining legacy codebases and adopting new languages for modern development needs.

Conclusion

Google uses a variety of programming languages, with C++, Python, Java, Go, JavaScript, and Kotlin being among the most prominent. The specific choice of language depends on the product or system being developed, with each language offering different strengths in terms of performance, scalability, and developer productivity.

Key Takeaways:

• C++ and Go are favored for high-performance backend systems and infrastructure.
• Python is dominant in AI, machine learning, and automation tasks.
• Java and Kotlin are widely used in Android development and Google Cloud.
• JavaScript and TypeScript are central to web development.
• Dart is growing in importance for cross-platform app development using Flutter.