Update 2010/04/25: A built-in feature like this seems to be around the corner. Note the "Linked" column on the right – this has been deployed exprimentally on Meta, but I suspect it won't be long before it's on all trilogy sites. So HREF Overflow is probably close to no-longer-relevant – thanks Jeff, I had just found the killer business model for making loads of money with this. No, really.

Update 2010/04/11: Now with data from the April data dump. This time, it also includes references made in comments (although you can hide these if you want to).

Update 2010/03/19: Since features like this have again been requested recently, I decided to finally update HREF Overflow. It's still based on the data dump, so no realtime data. But since I've simplified the process of updating the data, I'll be able to put the coming data dumps into it rather quickly. It now includes cross links between all four sites of the trilogy.

What is HREF Overflow?

When you have found an interesting question (say, "How do I do X?") on (e.g.) Stack Overflow, and you would like to read other similar question threads, one way to find such threads is to find out what other questions on the trilogy link back to "How do I do X". Which is what HREF Overflow does.

It shows you all* questions and answers on the trilogy that have links to the question you're interested in (or to one of its answers).

* All it knows about, that is. As mentioned, this isn't real-time data.

How can I use it?

There are two ways to query HREF Overflow. The first is to go to


where QUESTION_ID is the numerical question id that appears in the URL of the question, and SITE is one of so, su, sf, and meta. For backwards compatibility, the SITE/ part is optional and defaults to so/.

The second way is to create a bookmark called "What links to this?" (or the like) that changes the location to http://hrefoverflow.appspot.com/referrer (there's a bookmarklet on the page that you can just drag to your bookmark bar).

When you request /referrer from HREF Overflow, it will pull out the information to the question you're coming from (unless, of course, your browser hides the referrer). You may also request /referer, so it's up to you whether orthographical or technical specs are more important to you.


  • 5
    Clicked on star to make it glow. – random Sep 13 '09 at 16:18
  • Are links in comments also tracked? – sth Apr 3 '10 at 17:13
  • @sth: Not currently. I'm thinking about adding that into the next version, although I seem to recall I had a good reason against this. Hmmm... – balpha Apr 5 '10 at 19:39
  • @sth: It now includes links in comments. – balpha Apr 11 '10 at 8:31
  • Yup, Jeff is advertising the new feature quite aggressively ;-) – Arjan Apr 25 '10 at 13:43

No love for the rest of the trilogy sites?

One possible suggestion would be to hook your app up to the RSS feeds and index those posts, therefore you don't have a month old data.

  • 3
    edit: this is no longer true - the dump is now available for all sites. The dump only exists for SO, not the other sites, so getting the data would require scraping the question pages. But the RSS idea is good. – Kyle Cronin Sep 13 '09 at 21:00
  • Ahhhh, didn't think of that. – Josh Hunt Sep 13 '09 at 21:29
  • I like the RSS idea, I'll look into that. The App Engine cronjobs must be good for something... – balpha Sep 14 '09 at 12:16
  • 2
    It now includes all four trilogy sites. Still no realtime data, though. – balpha Mar 19 '10 at 18:05
  • You should switch to the API now. – uɐɯsO uɐɥʇɐN Jun 19 '10 at 21:44

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