Rotating Proxies for web scraping

I've setted up rotating proxies using HAProxy + DeleGate + Multiple Tor Instances. With Tor you don't have good control of bandwidth and latency but it's useful for web scraping. I've just published an article on the subject: Running Your Own Anonymous Rotating Proxies

Edit: There is even Python wrapper for gimmeproxy: https://github.com/ericfourrier/gimmeproxy-api

If you don't mind Node, you can use proxy-lists to collect public proxies and check-proxy to check them. It's exactly how https://gimmeproxy.com works, more info here

Make your crawler have a list of proxies and with each HTTP request let it use the next proxy from the list in a round robin fashion. However, this will prevent you from using HTTP/1.1 persistent connections. Modifying the proxy list will eventually result in using a new or not using a proxy.

Or have several connections open in parallel, one to each proxy, and distribute your crawling requests to each of the open connections. Dynamics may be implemented by having the connetor registering itself with the request dispatcher.