Proxy extensions range from simple switchers that toggle between proxy configurations you already have, to extensions that provide their own free proxy servers. The two work very differently: a switcher just manages settings you control, while a free proxy service routes your traffic through servers you don't own, which carries real privacy trade-offs worth understanding first.
Proxy switchers vs built-in proxy services
A proxy switcher extension lets you save several proxy server configurations, such as one for work and one for testing, and change between them from the toolbar instead of Chrome's settings menu. An extension that also provides its own free proxy servers is a different product: it's routing your traffic through infrastructure it controls, so it deserves more scrutiny than a switcher managing your own settings.
What to check before using a free proxy extension
Free proxy extensions for Chrome need to fund their servers somehow, which sometimes means logging your browsing, injecting ads, or selling bandwidth. Check for a clear privacy policy that states what is logged, whether traffic is encrypted between you and the proxy, and whether the extension works only through the browser or reroutes your whole device.
Permissions a proxy extension needs
A proxy extension needs Chrome's proxy permission to change your connection settings, and it may need host permissions if it manages per-site rules. It should not need access to read the content of every page you visit unless that's part of a specifically stated feature, since routing traffic and reading page content are separate jobs.