I found a free proxy on the internet. Why doesn't it work in Instafollowers?

The reason it doesn't work isn't Instafollowers. The overwhelming majority of free proxies stop working a few hours after they're published on the web, simply because the provider finds the error and closes the loophole that made them free in the first place, or they have been spammed to death.

The rest might still work, but rest assured that Instagram has found them before you found them and they flag the proxy. Using it will put your account at risk! So in simple terms: free proxies - NO!

Proxies cost money, and good proxies cost a lot of money. Precisely for that reason Instafollowers can be a free service only, because we ask users to bring their own proxies. 

My proxy doesn't work on the system? It does work elsewhere...

Did your proxy come with username & password? If not, it is IP authorized and you need to whitelist instafollowers' server IP address. It is 104.225.142.190. Ask your proxy provider how to do this. Even with username & password, some (very few) providers additionally limit by IP. Same procedure as above. 

Did you order HTTP proxies? Instafollowers (as most other systems) doesn't work with SOCKS. A rare problem, but be aware.

Did you enter the proxy string in a correct way? The formats are http://proxyuser:proxypass@1.2.3.4:3031 or (IP auth) http://1.2.3.4:3031, where 1.2.3.4 is either a group of IPv4 numbers or a name, like resi.monsterlabs.io, and 3031 stands for the port number. 

If all that is checked, there still is a 3% chance that instafollowers doesn't accept the proxy, because it's too slow or sends responses in a non-standard way. In that case please contact me via the help desk. I might be able to help.