koa-router is a routing library designed specifically for Koa, a lightweight and flexible Node.js web framework. It allows developers to define routes and middleware in a clean and organized manner, making it easier to build RESTful APIs and web applications. While koa-router is a powerful tool for Koa applications, there are several alternatives in the Node.js ecosystem that also provide robust routing capabilities. Here are a few notable alternatives:

• express is one of the most popular web frameworks for Node.js. It offers a minimalistic and flexible approach to building web applications and APIs. Express provides a powerful routing system that allows developers to define routes, middleware, and error handling in a straightforward manner. Its extensive ecosystem of middleware and plugins makes it a versatile choice for a wide range of applications, from simple APIs to complex web applications.
• fastify is a fast and low-overhead web framework for Node.js, designed for performance and scalability. Fastify features a powerful routing system that supports asynchronous programming and provides built-in schema validation for request and response payloads. If performance is a top priority for your application, Fastify is an excellent choice, as it is optimized for speed while still being easy to use and extend.
• hapi is another robust framework for building web applications and services in Node.js. It emphasizes configuration over code and offers a rich set of features, including a powerful routing system, input validation, caching, and authentication. Hapi is well-suited for building large-scale applications where maintainability and extensibility are crucial.
• sails is a full-featured MVC framework for building Node.js applications, particularly suited for building APIs and real-time applications. Sails is built on top of Express and provides a powerful routing system, along with features like data-driven APIs and WebSocket support. If you're looking to build a feature-rich application with a strong emphasis on convention over configuration, Sails is a great option.

To see how koa-router compares with express, fastify, hapi, and sails, check out the comparison: Comparing express vs fastify vs hapi vs koa-router vs sails.