baseURL

BaseUrl is a term used in web development to denote the canonical root URL against which relative URLs are resolved. It provides a single reference point for constructing and validating links, assets, and API endpoints. In code and configuration, baseUrl helps ensure consistency when resources are moved or when multiple environments (development, staging, production) are used.

In HTML, the base element can specify a base URL for all relative URLs in a document. If present, links, image sources, and form actions are resolved relative to that base. If the base tag is absent, the document's own URL serves as the base.

Many web applications and libraries expose a baseUrl configuration value to simplify API calls and resource loading. For example, a client might set baseUrl to https://api.example.com/v1 and then construct endpoints by appending paths like /users or /posts.

URL resolution rules: if a URL is absolute, it uses that. If it is relative, it is joined to the baseUrl, with careful handling of trailing slashes. Incorrect handling can create double slashes or broken links.

Security and maintenance considerations: baseUrl can affect redirects and cross-origin requests. Misconfigurations may enable open redirects or cross-site request forgery protections to be bypassed if relative links are not properly validated.

In practice, baseUrl is a simple but central concept for consistent URL management across front-end and back-end systems.