I have been looking for a caching HTTP proxy for Linux with the following properties:
Stand-alone: I'd rather not have to mess with e.g. my existing Apache or Squid configuration.
Low-latency: I.e. it should forward any data as it is retrieved, without waiting for the whole file to be downloaded first. That said, its overall performance is not of particular concern - usually it will only have at most one or two clients, downloading files in the 1-100MB range.
Caching using a format that allows the cached files to be used and/or modified directly. E.g.
http://example.com/a/b/file.txtcould be placed in
(Optional) A degree of configurability so that e.g. all
www*.example.comURLs would map to the same directory to avoid duplicating mirrors. A Python program that one can modify a bit could also be suitable...
I don't need to actually modify headers or file content - the proxy will be mostly used to share software update files to several VMs and physical machines without straining the connection to the Internet unnecessarily.