url-join is a utility library for constructing URLs by joining path segments together. It simplifies the process of creating valid URLs by handling edge cases such as trailing slashes and ensuring that segments are properly formatted. This makes it a handy tool for developers who need to build dynamic URLs in their applications. While url-join is a great option for URL construction, there are several alternatives that also provide useful functionalities. Here are a few:

• query-string is a library for parsing and stringifying URL query strings. It allows developers to easily manipulate query parameters, making it simple to create or modify URLs with complex query strings. If your primary focus is on handling query parameters rather than constructing full URLs, query-string is an excellent choice.
• uri-js is a comprehensive library for working with URIs (Uniform Resource Identifiers). It provides a wide range of functionalities for parsing, resolving, and manipulating URIs, making it suitable for more complex use cases. If you need to handle various aspects of URIs beyond just URL construction, such as validation or normalization, uri-js offers a robust solution.
• url-parse is a library that allows developers to parse URLs into their components, such as protocol, hostname, path, and query string. It also supports URL resolution and manipulation. If you need to dissect URLs and work with their individual components, url-parse is a great tool to consider.
• url-template is a library for working with URL templates, allowing developers to create and expand URLs based on predefined templates. This can be particularly useful for APIs that require dynamic URL construction based on variable parameters. If your application relies on templated URLs, url-template can simplify that process.

To see how url-join compares with query-string, uri-js, url-parse, and url-template, check out the comparison: Comparing query-string vs uri-js vs url-join vs url-parse vs url-template.