Yes, it is true that ASP.NET Web API has largely replaced WCF (Windows Communication Foundation) for building web services in the ASP.NET ecosystem. While WCF is still supported and can be used in specific scenarios, ASP.NET Web API (now known as ASP.NET Web API 2 or simply ASP.NET Core Web API in newer versions) offers a more modern and lightweight approach to building HTTP-based services.

Here are a few reasons why ASP.NET Web API is commonly preferred over WCF for building web services:

Simplicity and ease of use: ASP.NET Web API simplifies the process of building RESTful APIs by providing a straightforward programming model and convention-based routing. It focuses on HTTP and provides out-of-the-box support for content negotiation, routing, and model binding, making it easier to develop and maintain web services.

Lightweight and performance-oriented: ASP.NET Web API is designed to be lightweight and optimized for high performance. It leverages the capabilities of the ASP.NET Core platform, which is known for its high-performance, cross-platform runtime. ASP.NET Web API allows for more efficient handling of HTTP requests and responses, making it well-suited for building scalable and high-performance APIs.

Support for modern web standards: ASP.NET Web API has robust support for modern web standards and technologies. It easily integrates with JSON, XML, and other content types, supports HTTP methods and status codes, and offers features like content negotiation, authentication, and authorization. It also works seamlessly with modern client frameworks and technologies such as Angular, React, or mobile apps.

Cross-platform compatibility: ASP.NET Web API is built on the ASP.NET Core platform, which is cross-platform and can run on Windows, Linux, and macOS. This cross-platform compatibility allows developers to build and deploy web APIs on a variety of platforms and hosting environments.

Ongoing development and community support: ASP.NET Web API is actively maintained and enhanced by Microsoft, with regular updates and improvements. The ASP.NET Core community is vibrant and continually contributes to the growth and support of the framework. This ensures that ASP.NET Web API remains up-to-date, secure, and aligned with the latest industry standards and best practices.

While WCF still has its place and may be preferred for certain scenarios, such as building SOAP-based services or integrating with legacy systems, ASP.NET Web API has emerged as the primary choice for building modern, lightweight, and scalable web APIs in the ASP.NET ecosystem.