# Is it legal to use the Content Delivery network (CDN) which belongs to Stack Exchange?

I want to use prettyprint JavaScript library in my blogs. This library is already hosted in CDN for Stack Overflow cdn.sstatic.net.

Is cdn.sstatic.net a public CDN?
Can I use it in my blog or website with out a fee?

Who should be contacted to get permission or approval?

EDIT : Thanks a lot every one for the valuable answers. Probably my questions aren't very clear, I will elaborate a bit on what I expect.

1) I want to have code formatting on my Blog.

• Have decided to use prettyprint since Stack Overflow uses it
• I like the output.

• Need cheapest and most effective solution.

Option 1 -- Create my own CDN .. Ruled out.

I neither have expertise nor resources to build a CDN

Option 3 -- use svn/trunk as suggested by @YOU

Not as fast, reliable or available as CDN

Option 4 -- Use microsoft CDN

They dont have prettyprint yet.

Option 5 -- Use cdn.sstatic.net

Mature and proven

The problem here is that Google CDN and Microsoft CDN have a clearly stated policy that it will be free for use for any registered user. I did not find similar stuff from Stack Overflow. I am not sure if cdn.sstatic.net is public in nature providing some kind of free service. @kev has clarified "The Stack Exchange CDN is intended for the benefit of serving Stack Exchange pages faster and not to benefit third parties"

Hence the question remains. Is it legal to use scripts from cdn.sstatic.net in my blog? (blog in this case can be on a private server or hosted like in blogspot)

I believe cdn.sstatic.net is owned by Stack Exchange.

Does Stack Exchange have any policy to allow such use?

Who should be contacted to get permission or approval?

Summary of the answers based on responses above discussions.

1) It is illegal to use scripts hosted on cdn.sstatic.net for personal blogs or a hosted blog.

2) Stack Exchange does not have any policy or service to allow such use.

3) The Team at Stack Overflow should be contacted for approval.

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## migrated from programmers.stackexchange.comJun 27 '11 at 4:09

This question came from our site for professional programmers interested in conceptual questions about software development.

Wow, that must be a massive file and you must get such awesome traffic that you'd want to stea... borrow someone else's bandwidth to serve it! –  Won't Jun 27 '11 at 13:34
IMO, this is a job for Google, not SO. Until they do it, self-hosting is the way to go –  Pëkka Jun 27 '11 at 16:58
I don't think the OP really means legal, but probably something closer to Ethical. Legality would be constructed by evaluating the involved countries and all that noxious mess. –  OldTroll Jun 27 '11 at 17:16
updated my answer: short version: no. Longer version: talk to Google about it. –  Jeff Atwood Jun 28 '11 at 0:03
Here I built this for you & the open source community: opensource.maxcdn.com/javascript/prettify more projects to come (Stack Overflow uses the same CDN). –  jdorfman Aug 27 '11 at 1:19
That's a good news. Thanks a lot. Can you please clarify Is cdn.sstatic.net same as opensource.maxcdn.com? how are they related ? –  kiran.kumar M Aug 29 '11 at 10:50

No, you should not use our CDN in this manner. We would consider it abuse, and depending on my general mood on a particular day, we might go out of our way to break you.

This is a de-facto Google developed library. Unfortunately, Google doesn't host prettify, but should:

Is there a Content Delivery Network (CDN) that hosts Google Code Prettify?

You should heavily lobby Google to host this.

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you could replace the js content with something pretty interesting when accessed like that :) –  davidsleeps Jun 28 '11 at 0:06
May I suggest using it to somebody I don't particularly like? –  kiamlaluno Jun 28 '11 at 6:47
What about applications that use the 'markdown_extensions' field in the /sites API route? Would they be able to use the SE hosted versions...? Consider that you have a custom configuration for MathJax and allowing Stack Apps applications to use your version would guarantee some consistency with the main site that uses it. –  uɐɯsO uɐɥʇɐN Jun 28 '11 at 19:31

Even if you could and it was allowed, you're introducing a dependency that you have zero control of...

Edit
my particular view is that they wouldn't want you to do this (but that you shouldn't want to do it anyway)

Edit 2

Who should be contacted to get permission or approval?

team@stackoverflow.com

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I am already dependent on google. (I am on blogspot). Adding another dependency wont hurt. I think regular backup of the work will help address the availability issue(just in-case if google decides to go-offline) of the content. Immediate advantage for me is my blog will load faster. –  kiran.kumar M Jun 27 '11 at 4:57

Many people just use it from google code repository.

May be you just use it like that too?

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Nothing's stopping them from doing referrer checking, thus breaking all of your sites without your control.

Your dependency on Google is fine because they've publicly stated that they're hosting this just to ease everyone's burden and it's free for everyone to use. Stack Exchange has not said the same for their CDN content.

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@davidsleeps I am already dependent on google. (I am on blogspot). Adding another dependency wont hurt. I think regular backup of the work will help address the availability issue(just in-case if google decides to go-offline) of the content. Immediate advantage for me is my blog will load faster.

You can never say never, but, Google is likely to be more stable in the long term and their published url's less likely to change because they're actively providing this as a service to be relied upon. i.e. they want you to use their CDN (I'm guessing it allows them to collect even more "interesting" data for some purpose or another).

The Stack Exchange CDN is intended for the benefit of serving Stack Exchange pages faster and not to benefit third parties. The risk you have is that if the devs decide to restructure the Stack Exchange CDN content then your urls will go stale. So you could be playing catch up every now and again to fix your javascript src urls.

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Thanks @kev, I kept starting a comment reply to the op but sort of gave up because I figured he was justifying whilst knowing the answer already...but you have summed it up really well! –  davidsleeps Jun 27 '11 at 11:22
Thanks @kev Thanks @davisleeps. Request your attention to EDIT section in my question. –  kiran.kumar M Jun 27 '11 at 16:50

Most likely StackExchange is paying for sstatic.net services. Using their content to prettify and speed up your blog is in essence making StackExchange pay for the delivery of your blog.

Would you like someone else stealing your bandwidth, making you pay for the delivery of their content? Just because "it is already there"?

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The OP specifically asked for whether they allowed it. It looks to me like you are more or less restating the question. –  blubb Jun 27 '11 at 11:42
@Simon: I think (but I am not game to spend time to check) the question was edited since my answer. When I answered (which may have been some time after loading the page) it was worded differently. –  Marjan Venema Jun 27 '11 at 12:34
The question was there and worded the same in the first revision and you answered 2 hours after the second revision. I rest my case ;) –  blubb Jun 27 '11 at 13:28
@Simon: ok :) but I stand by my answer as not being a rewording of the question. OP asks whether it is allowed, I answer by telling him what his proposed use entails and whether he would like having it done to him. Possibly a bit long-winded, but a clear "no" if you ask me and not a restatement of the question. –  Marjan Venema Jun 27 '11 at 13:50