- Video embedding, such as Youtube, Vimeo, etc.
- Social sharing buttons for Facebook, Twitter, and others
- Advertising iframes
- Analytics and metric applications
- Use popular third-party libraries that have a large supporting community. These libraries tend to make regular updates and communicate with their community. You’ll also have fellow users to ask questions or express concerns.
- Use open-source libraries that provide access to the source code so you can identify any issues with quality or security loopholes.
- Make sure your chosen third-party libraries contain the correct licenses and specifications for whatever you intend to use the library for.
- Too many network requests to multiple servers
- Sending large, unoptimized images or videos
- Single-Point of Failures (SPOF) caused by incorrect script loading
- Lack of sufficient server compression
- Using legacy APIs known to be harmful to the user experience
These tools will highlight third-party applications used by the site, the amount of requests used for each application, and the time they take to load.
If you discover that you may not need a third-party application, you can perform an A/B test using Chrome DevTools network request blocking function. This allows you to see how your site would perform if you blocked the particular application.