WebAssembly in 2025: Why Use It in Modern Projects?
When discussing web development tech stack, JavaScript and frontend frameworks like Vue and React are the first to come to mind. But have you experienced how JavaScript, a powerful tool for creating interactive interfaces, faces performance limitations when executing resource-intensive tasks? Maybe you are curious how Zoom delivers real-time virtual backgrounds without a hitch or how Figma allows designers to collaborate on complex files in real time without lag. The answer is WebAssembly (Wasm), a tool that enables high-performance apps for gaming, data analysis, and virtual machines to run seamlessly in the browser.
In this blog post, we will explore how WebAssembly works, why it is actively supported by companies like Google, Unity, and Unreal Engine, and what new possibilities it opens for modern projects.
What is WebAssembly?
WebAssembly (Wasm) is a low-level binary instruction format that allows the execution of code written in efficient programming languages like C, C++, C#, Rust, and even Python at near-native speeds in the browser. Being compiled, not interpreted, WebAssembly speeds up page loading and code execution to near-native levels. It is especially important for resource-intensive apps such as games, graphic editors, and other CPU-intensive tasks.
Wasm is supported by all major modern browsers (Chrome, Firefox, Safari, and Edge). It allows developers to build complex and resource-intensive apps without using JavaScript as the only programming language. At the same time, Wasm doesn't replace JavaScript but enhances it. Developers can apply hybrid approaches for web development, namely, call Wasm modules from JavaScript, offloading performance-heavy tasks, such as video processing or working with large amounts of data, while keeping JavaScript's flexibility for UI and logic. WebAssembly runs in a sandbox, meaning it is isolated from the rest of the system. It provides an additional layer of security when running high-performance applications on the web.
How Does WebAssembly Work?
WebAssembly uses a compact binary format designed for fast execution across different operating systems and hardware architectures. Compared to text-based formats like JavaScript, Wasm loads and executes more efficiently due to its fixed instruction size and simplified structure. Wasm modules are typically smaller than equivalent JavaScript bundles, sometimes by 2x or more for optimized code, parsing faster and reducing load times. High-level languages such as C, C++, Rust, and others are compiled into WebAssembly bytecode. This compilation happens ahead of time (AOT), meaning that Wasm modules arrive in a ready-to-execute format, unlike JavaScript, which requires interpretation or Just-In-Time (JIT) compilation.
The WebAssembly execution process ensures high performance and strong security. Here's how it works:
The WebAssembly module is downloaded and undergoes a security check to ensure safe execution.
It is then compiled into machine code by the browser's Wasm engine.
Finally, it runs inside an isolated sandbox environment, preventing unauthorized access to the system.
Which languages can be compiled to Wasm?
Currently, more than 40 programming languages can be compiled into WebAssembly. Among them:
Rust → Built-in support via wasm-pack
C/C++ → Compiled using Emscripten
C#/.NET → Supported via Blazor WebAssembly
Java → Can be compiled using TeaVM, Bytecoder, or JWebAssembly with varying levels of completeness
Python → Pyodide brings Python to the browser by running a Wasm-compiled interpreter
TypeScript - AssemblyScript compiles a TypeScript-like language to Wasm
Kotlin - Supports Kotlin/Wasm, and TeaVM can also compile Kotlin to Wasm
Scala - Can be compiled using TeaVM
Perl - WebPerl is a port of the Perl interpreter to WebAssembly
Swift - SwiftWasm provides WebAssembly compilation support for Swift applications
What are WebAssembly Use cases?
In 2025, Wasm is used for more than just technical demos, it supports real-world applications across a variety of industries:
Gaming in the Browser
WebAssembly has transformed the approach to developing browser games. Thanks to Wasm's near-native performance, even demanding, console-quality games can run efficiently in a web browser with near-zero latency and without the need to install plugins. Platforms like Unity and Unreal Engine now compile game engines into Wasm. For instance, Angry Bots is a 3D action game developed by Unity Technologies, showcasing Unity's capabilities in the browser using WebAssembly and WebGL. Another example is Unity WebGL Games like Tanks! Unreal Engine has recently introduced support for WebGPU and WebAssembly in Unreal Engine 5, enhancing the performance and capabilities of browser-based games. For instance, the Lyra sample project has been successfully run entirely in the browser using WebGPU and WebAssembly.
High-Performing SaaS Applications
WebAssembly is used to develop web-based apps that require real-time processing, such as 3D modeling tools, graphic design software, and data visualization dashboards. One of the great examples of WebAssembly in action in this category is Figma, a popular interface design tool. Its smooth performance with complex vector editing and real-time collaboration showcases Wasm's strengths. Switching to WebAssembly to power its browser-based design tool allowed Figma to reduce the app loading time by 3x. Achieving the same level of responsiveness in pure JS would be a huge challenge.
AI & Machine Learning
WebAssembly is increasingly applied in artificial intelligence and machine learning. It allows developers to run machine learning models, such as face detection or object recognition, directly in web apps without significant latency. Using Wasm, developers can also create interactive features like recommendation systems or dynamic content personalization within web-based apps. By leveraging in-browser machine learning models compiled to Wasm, these features run efficiently, providing real-time performance with low power consumption, even on low-power devices. TensorFlow.js, an open-source JavaScript library for training and deploying machine learning models, has integrated a Wasm backend to improve performance. This backend is an alternative to the WebGL backend, offering fast CPU execution with minimal code changes. It enhances performance on devices that lack WebGL support or have a slow GPU. The Wasm backend supports various models, including BlazeFace, BodyPix, CocoSSD, Face Landmarks Detection, HandPose, and the KNN classifier. This support enables developers to implement real-time, interactive AI applications directly in the browser.
Audio and Video Editing
WebAssembly has unlocked new possibilities in audio and video processing, which traditionally rely on high-performance computing. With Wasm, developers can build sophisticated multimedia tools previously possible only with desktop software. Wasm's near-native speed facilitates the smooth execution of complex operations like encoding, decoding, and real-time effects. FFmpeg is an open-source software suite for handling video, audio, and other multimedia files. Projects like FFmpeg-Wasm enable high-speed video encoding and processing directly in the browser, so users can perform complex multimedia tasks without relying on server-side processing. Google Meet utilizes WebAssembly to implement background blur and replacement features during video calls. Squoosh is an image compression web app developed by Google that employs WebAssembly to perform real-time image compression directly in the browser without additional software installations.
Scientific computing
One of the main benefits of WebAssembly is its ability to handle computationally intensive tasks with outstanding efficiency. It speeds up computations when dealing with complex tasks, such as processing large sets of data, running detailed simulations, or solving complicated mathematical problems. JupyterLite, a web-based interactive computing environment, has integrated Wasm to execute Python code snippets directly in the browser, streamlining data analysis and visualization tasks without server dependencies. DuckDB, an in-browser analytical SQL engine, utilizes Wasm to perform complex data queries efficiently within web applications.
What are Limitations of WebAssembly?
Despite its advantages, WebAssembly also faces several limitations:
Complex Debugging: debugging WebAssembly code can be more difficult compared to JavaScript. The reason is that Wasm code is typically compiled from languages like C, C++, or Rust, resulting in binary formats that are not human-readable. Debugging tools are not yet as advanced, so it may take more time and effort to identify errors in the code.
Limited DOM Access: WebAssembly also does not have, at least for now, direct access to the browser's Document Object Model (DOM). It means that to manipulate DOM elements and interact with the user interface, it is necessary to rely on JavaScript as an intermediary, which can complicate the architecture of the application.
Limited Ecosystem: Although the WebAssembly ecosystem is actively developing, it is still not as extensive as the one of JavaScript. Some libraries and frameworks may not support Wasm or require additional integration efforts.
Memory Management: Wasm's memory management model can present challenges, especially for memory-intensive applications. Allocating large memory spaces may not be reliable across all browsers, particularly on mobile devices. JavaScript has a garbage collector (GC), but WebAssembly currently has no knowledge of that GC. Since wasm code uses JS code to interact with the DOM, this can be a source of memory leaks.
The Future of WebAssembly
Wasm continues to evolve and opens new horizons for web app development. In 2025, developers and the community expect a number of changes and upgrades:
WASI (WebAssembly System Interface)
We expect the ongoing development of WASI (WebAssembly System Interface) that provides access to system resources outside the browser (e.g., files, networking, environment variables). The launch of WASI 0.2 (Preview 2) was a significant milestone, enabling Wasm to operate beyond the browser environment and making it useful for server-side, cloud, and edge computing. WASI Preview 2 (WASI 0.2) has made significant progress but remains under development, with varying levels of support across different WebAssembly runtimes. For example, Wasmtime has integrated full support for WASI Preview 2, while Wasmer has added Preview 2 support in its 3.x/4.x releases and WasmEdge is making gradual progress toward implementation. WASI 0.3 is expected in the first half of 2025. This release aims to incorporate native asynchrony into the component model and then adjust the existing WASI 0.2 interfaces to use the new asynchrony capabilities.
Component Model:
The ongoing development of the WebAssembly Component Model aims to standardize how Wasm modules interact with each other regardless of the original programming language. Normally, programming languages have their own ecosystems and libraries. For example, a Python developer usually works with Python libraries, and a JavaScript developer uses JavaScript libraries. With the Component Model, different languages can be compiled into WebAssembly components. As a result, a Python developer can use a Rust library without worrying about compatibility, and a JavaScript developer can leverage Go libraries as long as they are compiled into Wasm components. This model enhances modularity and interoperability, enabling the composition of complex apps from reusable components.
Language Support and Ecosystem Expansion
The number of programming languages supporting compilation to Wasm is also expected to grow. This expansion fosters a more inclusive ecosystem, enabling developers from diverse language backgrounds to utilize Wasm's capabilities.
Performance Enhancements
Introducing features like garbage collection (GC), multithreading, and access to GPUs will further enhance Wasm's performance, making it more appealing for high-performance apps. GC is not yet universally supported across all browsers, but notably, Safari's integration of garbage collection in 2024 marked a significant step forward, with further optimizations anticipated in 2025.
Adoption, Tooling, and Emerging Use Cases
As the WebAssembly ecosystem matures, 2025 promises new tools and libraries to simplify development, lower the learning curve, and boost adoption. As of early 2025, WebAssembly powers over 3% of websites in Chrome (a figure likely higher across all browsers, per recent Web Almanac data). With enhancements like WASI and the Component Model, this upward trend should accelerate, making Wasm a staple in modern web stacks.
WebAssembly's evolution is already sparking cutting-edge applications. In gaming, Ambient, an open-source 3D engine, leverages Wasm and WebGPU to deliver immersive, multiplayer browser experiences rivaling native apps. For serverless computing, Fermyon's Spin uses Wasm to run microservices in the browser or cloud. At the edge, WasmEdge enables IoT devices like smart sensors to run AI models locally, slashing latency for real-time insights. Beyond traditional use cases, the lightweight and efficient nature of WebAssembly has led to ongoing discussions about using WebAssembly as an alternative to traditional containers, with efforts to integrate Wasm into Kubernetes environments (e.g., through projects like Krustlet and runwasi).
Conclusion
One of the major goals of WebAssembly is to be faster than JavaScript. So, if your project demands high performance, cross-platform support, or enhanced security, Wasm is a powerful tool to consider. However, JavaScript and modern frameworks might still be sufficient for simple web apps. In 2025, WebAssembly will continue to evolve and remain a critical tool for performance-driven apps. As browsers, cloud providers, and software ecosystems further embrace it, its role in modern development will only grow. While a key goal of WebAssembly is to outpace JavaScript in performance, its creators also aim for a portable, efficient runtime for any language—a vision advancing in 2025.
