Simply Testable vs Squid: What are the differences?
What is Squid? A caching proxy for the Web supporting HTTP, HTTPS, FTP, and more. Squid reduces bandwidth and improves response times by caching and reusing frequently-requested web pages. Squid has extensive access controls and makes a great server accelerator. It runs on most available operating systems, including Windows and is licensed under the GNU GPL.
Simply Testable can be classified as a tool in the "In-Browser Testing" category, while Squid is grouped under "Web Cache".
Squid is an open source tool with 578 GitHub stars and 204 GitHub forks. Here's a link to Squid's open source repository on GitHub.