Question: I put [a package on PyPi](http://pypi.python.org/pypi/powerlaw) for the first time ~2 months ago, and have made some version updates since then. I noticed this week the download count recording, and was surprised to see it had been downloaded hundreds of times. Over the next few days, I was more surprised to see the download count increasing by sometimes hundreds *per day*, even though this is a niche statistical test toolbox. In particular, older versions of package are continuing to be downloaded, sometimes at higher rates than the newest version.

What is going on here?

Is there a bug in PyPi's downloaded counting, or is there an abundance of crawlers grabbing open source code (as mine is)?

Answer: 
This is kind of an old question at this point, but I noticed the same thing about a package I have on PyPI and investigated further. It turns out PyPI keeps reasonably detailed [download statistics](http://pypi.python.org/stats/), including (apparently slightly anonymised) user agents. From that, it was apparent that most people downloading my package were things like "z3c.pypimirror/1.0.15.1" and "pep381client/1.5". (PEP 381 describes a mirroring infrastructure for PyPI.)

I wrote [a quick script](https://gist.github.com/Cairnarvon/4715057) to tally everything up, first including all of them and then leaving out the most obvious bots, and it turns out that **literally 99%** of the download activity for my package was caused by mirrorbots: 14,335 downloads total, compared to only 146 downloads with the bots filtered. And that's just leaving out the very obvious ones, so it's probably still an overestimate.

It looks like the main reason PyPI needs mirrors is because it has them.
Starting with Cairnarvon's summarizing statement: 

> 
> "It looks like the main reason PyPI needs mirrors is because it has them."
> 
> 
> 

I would slightly modify this: 

> 
> It might be more the **way** PyPI actually works and thus has to be mirrored, that might contribute an additional bit (or two :-) to the *real* traffic. 
> 
> 
> 

At the moment I think you MUST interact with the main index to know what to update in your repository. State is not simply accesible through timestamps on some publicly accessible folder hierarchy. So, the bad thing is, rsync is out of the equation. The good thing is, you MAY talk to the index through JSON, OAuth, XML-RPC or HTTP interfaces.

For XML-RPC:

```
$> python
>>> import xmlrpclib
>>> import pprint
>>> client = xmlrpclib.ServerProxy('http://pypi.python.org/pypi')
>>> client.package_releases('PartitionSets')
['0.1.1']

```

For JSON eg.:

```
$> curl https://pypi.python.org/pypi/PartitionSets/0.1.1/json

```

If there are approx. 30.000 packages hosted [[1](https://pypi.python.org/pypi)] with some being downloaded 50.000 to 300.000 times a week [[2](http://pypi-ranking.info/week)] (like distribute, pip, requests, paramiko, lxml, boto, paramike, redis and others) you really need mirrors at least from an accessibilty perspective. Just imagine what a user does when `pip install NeedThisPackage` fails: *Wait*? Also company wide PyPI mirrors are quite common acting as proxies for otherwise unrouteable networks. Finally not to forget the wonderful multi version checking enabled through virtualenv and friends. These all are IMO legitimate and potentially wonderful uses of packages ...

In the end, you never know what an agent *really* does with a downloaded package: Have N users really use it or just overwrite it next time ... and after all, IMHO package authors should care more for **number and nature of uses**, than the pure *number of potential users* ;-) 

---

Refs: The guestimated numbers are from <https://pypi.python.org/pypi> (29303 packages) and <http://pypi-ranking.info/week> (for the weekly numbers, requested 2013-03-23).