Can third-party libraries be used in LWC?

Third-party libraries can indeed be used in Lightning Web Components (LWC), and they can be included either as static resources or accessed using Content Delivery Networks (CDNs). Utilizing static resources allows developers to bundle external libraries together with their application code, ensuring that the specific versions of the libraries are always available. This is particularly beneficial for maintaining consistency across environments and ensuring that the application behaves as expected.

Using CDNs is another flexible option, as it allows developers to leverage libraries hosted externally, which can reduce load times and take advantage of optimized delivery practices. By accessing libraries directly from a CDN, developers can ensure their application can take advantage of the latest versions of those libraries without needing to manage those files within Salesforce.

The other options presented do not accurately reflect the capabilities of LWC regarding third-party libraries. Only Salesforce libraries being permitted or the restriction to open-source libraries does not align with LWC's design, which aims to facilitate rich integration with various JavaScript resources. Likewise, the notion that integration must occur solely through Salesforce APIs is more restrictive than necessary, as LWC supports broader functionality, including the use of external libraries.