Top Programming Languages Used in the Threads App of Instagram

When Instagram launched its Twitter-like microblogging app called Threads, it instantly caught the attention of tech enthusiasts, developers, and digital marketers. As a product of Meta (formerly Facebook Inc.), Threads is a high-performance, real-time social app that supports image, video, and text content. But behind its sleek interface and seamless user experience lies a complex tech stack powered by a blend of modern programming languages and frameworks.

1. Python – The Brain Behind Server-Side Logic

Python plays a significant role at Meta, and Threads is no exception. Python is used extensively in backend development, automation, data analysis, and AI/ML models within the Meta ecosystem.

Why Python?

Scalability: Python frameworks like Django and Flask support rapid development and scale well.

Machine Learning Integration: For recommendation systems and content moderation, Python works well with libraries like TensorFlow, PyTorch, and scikit-learn.

Developer Productivity: Python’s clean syntax and large support libraries speed up development cycles.

Meta has a long history of using Python internally, and the backend logic of Threads—such as handling API requests, session management, and user data processing—is likely powered in part by Python services.

2. React Native & JavaScript – The Core of Cross-Platform Mobile UI

To ensure cross-platform compatibility and a consistent user interface across Android and iOS, Threads uses React Native, which is based on JavaScript.

Why React Native?

Code Reusability: With React Native, much of the codebase can be shared across iOS and Android platforms.

Live Reloading: Developers can see changes instantly, speeding up UI development.

Community Support: React Native has a vast developer community and robust plugin support.

The Threads app delivers a responsive UI that loads in milliseconds and offers native-like transitions. This performance is possible thanks to JavaScript, the underlying language of React Native, along with JSX for component structuring.

3. Java/Kotlin – The Backbone of Android Development

Even though React Native is used, certain components of Threads—especially those requiring native Android capabilities—are likely written in Java and Kotlin.

Why Java/Kotlin?

Android SDK Compatibility: Java has been the traditional language for Android, while Kotlin is now the preferred official language.

Performance Optimization: For resource-intensive features like real-time notifications or camera modules, native code performs better than JavaScript.

Security: Handling permissions and device-level controls is easier in Java/Kotlin.

Meta often combines cross-platform frameworks with native code for hybrid development to get the best of both worlds.

4. Swift/Objective-C – For Native iOS Features

Just like Java and Kotlin are important for Android, Swift and Objective-C are used to power platform-specific features in iOS for the Threads app.

Why Swift?

Apple Ecosystem Integration: Swift is built for iOS and integrates seamlessly with Apple APIs.

Speed and Security: Swift is faster and more secure compared to Objective-C.

Ease of Use: The language is concise and expressive, leading to fewer bugs.

Core iOS features such as notifications, camera access, and performance monitoring are often written in Swift, even when the app is largely built using React Native.

5. Hack (HHVM) – Meta’s Server-Side Powerhouse

Meta developed Hack, a programming language derived from PHP, that runs on the HHVM (HipHop Virtual Machine). It's used widely across Meta products including Facebook and Instagram, and by extension, Threads.

Why Hack?

Static Typing + Dynamic Typing: Hack blends the flexibility of PHP with the safety of statically typed languages.

Performance: HHVM compiles code just-in-time (JIT), providing high performance for web applications.

Security: Type annotations and improved error checking to reduce runtime failures.

The hack is commonly used in Meta’s backend for handling millions of user requests, message queuing, and user session management.

6. SQL and GraphQL – For Efficient Data Querying

The Threads app needs to access and manage a massive amount of user data, media, likes, comments, and follower networks. For this, SQL and GraphQL are used.

Why SQL?

Relational Database Access: SQL is the standard for querying relational databases, which may store user data, posts, and comments.

Data Integrity: SQL-based systems like MySQL or PostgreSQL offer ACID compliance and complex query capabilities.

Why GraphQL?

Flexible Queries: GraphQL allows clients to specify exactly what data they need, reducing over-fetching.

Real-Time Updates: Threads likely use GraphQL subscriptions for real-time updates, such as new replies and notifications.

GraphQL, developed by Facebook, is widely used in its ecosystem to optimize frontend and backend communication.

7. Rust and C++ – For Performance-Critical Components

Meta has started adopting Rust in security-critical and performance-heavy parts of its apps. C++ is also widely used for performance optimization.

Why Rust?

Memory Safety: Rust offers safety without a garbage collector.

Concurrency: Rust makes it easier to write multi-threaded code without data races.

Why C++?

Performance: Used for backend systems that require low-level memory control, such as image processing, media compression, and video streaming.

Legacy Integration: C++ codebases are deeply integrated into Meta’s infrastructure.

Some backend systems, such as media delivery servers or content distribution networks, may be powered using these high-performance languages.

Whether you're a beginner or a seasoned developer, understanding the Threads tech stack can guide your own learning path. So next time you scroll through your Threads feed, remember—it’s backed by a beautifully orchestrated ensemble of programming languages working seamlessly behind the scenes.