# WebAssembly System Interface

> modular system interface for WebAssembly

**Wikidata**: [Q114968900](https://www.wikidata.org/wiki/Q114968900)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/WebAssembly_System_Interface)  
**Source**: https://4ort.xyz/entity/webassembly-system-interface

## Summary
The WebAssembly System Interface (WASI) is a modular system interface designed for WebAssembly. Developed by the Bytecode Alliance, it serves as a sandboxed application binary interface (ABI) and runtime system that enables WebAssembly code to execute efficiently across different operating systems and platforms.

## Key Facts
- **Aliases:** WASI
- **Developer:** Bytecode Alliance
- **Category:** Technical specification, application binary interface (ABI), and run-time system
- **Parent Ecosystem:** Part of WebAssembly (WASM)
- **Website:** https://wasi.dev/
- **Source Code:** Hosted at https://github.com/WebAssembly/WASI
- **License:** W3C Community Contributor License Agreement
- **Influences:** Designed based on concepts from POSIX and CloudABI (Capsicum)
- **Classifications:** Subclass of operating system; instance of cross-platform software and sandbox.

## FAQs
### Q: What exactly is the WebAssembly System Interface (WASI)?
A: WASI is a technical specification and application binary interface that provides a modular system interface for WebAssembly. It allows WebAssembly code to interact with the underlying operating system in a secure, sandboxed environment.

### Q: Who develops and maintains WASI?
A: WASI is developed by the Bytecode Alliance. It operates under the W3C Community Contributor License Agreement.

### Q: What technical standards influenced the design of WASI?
A: The design of WASI was majorly influenced by POSIX and CloudABI (specifically concepts related to Capsicum).

## Why It Matters
The WebAssembly System Interface (WASI) represents a critical evolution in the WebAssembly ecosystem, extending its utility beyond the web browser. By defining a standardized application binary interface (ABI), WASI solves the problem of platform dependency for compiled code, allowing WebAssembly modules to run seamlessly across different operating systems—such as Windows, macOS, and Linux—without modification.

This cross-platform capability is significant because it allows developers to write code once in languages like C, C++, or Rust and deploy it anywhere WebAssembly runs. Furthermore, WASI emphasizes security through sandboxing, ensuring that applications have controlled access to system resources. By leveraging influences from POSIX and CloudABI, it provides a familiar yet modern environment for system-level programming, making it a key technology for portable, efficient, and secure computing outside the traditional web environment.

## Notable For
- **Portability:** Enables WebAssembly to function as a "write once, run anywhere" technology for native applications.
- **Security Architecture:** Implements a sandboxed environment, inheriting security concepts from CloudABI and Capsicum.
- **Standardization:** Acts as a formal technical specification for the Web Assembly Binary Format ecosystem.
- **Modularity:** Designed as a modular interface rather than a monolithic one, allowing for flexible implementation.
- **Governance:** Developed under the stewardship of the Bytecode Alliance and the W3C community process.

## Body

### Technical Definition and Classification
WASI is defined as a modular system interface and a technical specification. Structured as an application binary interface (ABI) and a run-time system, it functions as a subclass of an operating system interface. It is categorized as cross-platform software and a computing platform.

### Ecosystem and Development
WASI is an integral part of the WebAssembly (WASM) ecosystem. The project is developed by the **Bytecode Alliance** and utilizes the **Web Assembly Binary Format**. The intellectual property is managed under the **W3C Community Contributor License Agreement**.

### Design and Influences
The architecture of WASI is not an entirely new invention but a refinement of existing system standards. Its major influences are **POSIX** (Portable Operating System Interface) and **CloudABI**. Specifically, it draws upon the capability-based security concepts found in **Capsicum**. This lineage allows WASI to provide a robust, sandboxed environment for executing code while maintaining a standard interface for system calls.

### Resources
The official resources for the WebAssembly System Interface include its primary website at **wasi.dev** and its source code repository hosted on **GitHub** at `https://github.com/WebAssembly/WASI`.

## References

1. [Release 0.2.0. 2024](https://github.com/WebAssembly/WASI/releases/tag/v0.2.0)
2. [Release 0.2.1. 2024](https://github.com/WebAssembly/WASI/releases/tag/v0.2.1)
3. [Release 0.2.2. 2024](https://github.com/WebAssembly/WASI/releases/tag/v0.2.2)
4. [Release 0.2.3. 2024](https://github.com/WebAssembly/WASI/releases/tag/v0.2.3)
5. [Release 0.2.4. 2025](https://github.com/WebAssembly/WASI/releases/tag/v0.2.4)
6. [Release 0.2.5. 2025](https://github.com/WebAssembly/WASI/releases/tag/v0.2.5)
7. [Release 0.2.6. 2025](https://github.com/WebAssembly/WASI/releases/tag/v0.2.6)
8. [Release 0.2.7. 2025](https://github.com/WebAssembly/WASI/releases/tag/v0.2.7)
9. [Release 0.2.8. 2025](https://github.com/WebAssembly/WASI/releases/tag/v0.2.8)
10. [Release 0.2.9. 2025](https://github.com/WebAssembly/WASI/releases/tag/v0.2.9)
11. [Release 0.2.10. 2026](https://github.com/WebAssembly/WASI/releases/tag/v0.2.10)
12. [Release 0.2.11. 2026](https://github.com/WebAssembly/WASI/releases/tag/v0.2.11)
13. [Source](https://github.com/WebAssembly/WASI/blob/2980bb39e1d2a4a2adae4748908cb4325cd41a26/README.md)